PHP and MySQL Interview Question and answer

PHP AND MYSQL INTERVIEW QUESTIONS & ANSWERS

1. What are the differences betweenGET andPOST methods in form submitting, give the case where we can use get and we can use post methods?

Answer: On the server side, the main difference between GET and POST is where the submitted is stored. The $_GET array stores data submitted by the GET method. The $_POST array stores data submitted by the POST method.

On the browser side, the difference is that data submitted by the GET method will be displayed in the browser’s address field. Data submitted by the POST method will not be displayed anywhere on the browser.

GET method is mostly used for submitting a small amount and less sensitive data.

POST method is mostly used for submitting a large amount or sensitive data.

2. Who is the father of php and explain the changes in php versions?

Answer: Rasmus Lerdorf for version changes go tohttp://php.net/ Marco Tabini is the founder and publisher of php|architect.

3. How can we submit from without a submit button?

Answer: We can use a simple JavaScript code linked to an event trigger of any form field. In the JavaScript code, we can call the document.form.submit() function to submit the form. For example:

4. How many ways we can retrieve the date in result set of mysql Using php?

Answer: As individual objects so single record or as a set or arrays.

mysql_fetch_array – Fetch a result row as an associative array, a numeric array, or both
mysql_fetch_assoc – Fetch a result row as an associative array
mysql_fetch_object – Fetch a result row as an object
mysql_fetch_row —- Get a result row as an enumerated array

5. What is the difference between mysql_fetch_object and mysql_fetch_array?

Answer:  MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array.

6. What is the difference between $message and $$message?

Answer:  They are both variables. But $message is a variable with a fixed name. $$message is a variable who’s name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.

7. How can we extract string ‘abc.com ‘ from a string  ‘http://info@a…’ using regular _expression of php?

Answer: We can use the preg_match() function with “/.*@(.*)$/” as the regular expression pattern. For example:
preg_match(“/.*@(.*)$/”,”http://info@abc.com”,$data);
echo $data[1];

8. How can we create a database using php and mysql?

Answer: PHP: mysql_create_db()
Mysql: create database;

9. What are the differences between require and include, include_once?

File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once(). This will prevent problems with function redefinitions, variable value reassignments, etc.

10. Can we use include (“abc.php”) two times in a php page “makeit.php”?

Answer: Yes we can include.

11. What are the different tables present in mysql, which type of table is generated when we are creating a table in the following

syntax: create table employee(eno int(2),ename varchar(10)) ?

Answer: Total 5 types of tables we can create            1. MyISAM     2. Heap     3. Merge     4. InnoDB     5. ISAM     6. BDB
MyISAM is the default storage engine as of MySQL 3.23.

12. Functions in IMAP, POP3 AND LDAP?

Answer:

13. How can I execute a php script using command line?

Answer:  Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program. Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

14. Suppose your ZEND engine supports the mode <? ?> Then how can u configure your php ZEND engine to support <?php ?> mode ?

Answer:  If you change the line: short_open_tag = off in php.ini file. Then your php ZEND engine support only <?php ?> mode.

15. Shopping cart online validation i.e. how can we configure the paypals?

16. What is meant by nl2br()?

Answer:nl2br — Inserts HTML line breaks before all newlines in a string string nl2br (string); Returnsstring with ‘<br />’ inserted before all newlines.
For example: echo nl2br(“god bless\n you”) will output “god bless \n you” to your browser.

 

17. Draw the architecture of ZEND engine?

18. What are the current versions of apache, php, and mysql?

Answer: PHP: php5.1.2

MySQL: MySQL 5.1

Apache: Apache 2.1

19. What are the reasons for selecting lamp (Linux, apache, mysql, php) instead of combination of other software programs, servers and operating systems?

Answer: All of those are open source resource. Security of linux is very very more than windows. Apache is a better server that IIS both in functionality and security. Mysql is world most popular open source database. Php is more faster that asp or any other scripting language.

20. How can we encrypt and decrypt a data present in a mysql table using mysql?

Answer: AES_ENCRYPT () and AES_DECRYPT ()

21. How can we encrypt the username and password using php?

Answer: You can encrypt a password with the following Mysql>SET
PASSWORD=PASSWORD(“Password”);

We can encode data using base64_encode($string) and can decode using

base64_decode($string);

22. What are the features and advantages of OBJECT ORIENTED PROGRAMMING?

Answer: One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is
procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns.

For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.

23. What are the differences between PROCEDURE ORIENTED LANGUAGES AND OBJECT ORIENTED LANGUAGES?

Answer:Traditional programming has the following characteristics: Functions are written sequentially, so that a change in programming can affect any code that follows it. If a function is used multiple times in a system (i.e., a piece of code that manages the
date), it is often simply cut and pasted into each program (i.e., a change log, order function, fulfillment system, etc). If a date change is needed (i.e., Y2K when the code needed to be changed to handle four numerical digits instead of two), all these pieces of code must be found, modified, and tested.

Code (sequences of computer instructions) and data (information on which the instructions operates on) are kept separate. Multiple sets of code can access and modify one set of data. One set of code may rely on data in multiple places. Multiple sets of code and data are required to work together. Changes made to any of the code sets and data sets can cause problems through out the system.

Object-Oriented programming takes a radically different approach:

Code and data are merged into one indivisible item – an object (the term “component” has also been used to describe an object.) An object is an abstraction of a set of real-world things (for example, an object may be created around “date”) The object would contain all information and functionality for that thing (A date object it may contain labels like January, February, Tuesday, Wednesday. It may contain functionality that manages leap years, determines if it is a business day or a holiday, etc., See Fig. 1). Ideally, information about a particular thing should reside in only one place in a system. The information within an object is encapsulated (or hidden) from the rest of the system.

A system is composed of multiple objects (i.e., date function, reports, order processing, etc., See Fig 2). When one object needs information from another object, a request is sent asking for specific information. (for example, a report object may need to know what today’s date is and will send a request to the date object) These requests are called messages and each object has an interface that manages messages.

OO programming languages include features such as “class”, “instance”, “inheritance”, and “polymorphism” that increase the power and flexibility of an object.

24. What is the use of friend function?

Answer: Friend functions
Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class whichnames them as a friend, as if they were themselves members of that class.

A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.

class mylinkage {

private:
mylinkage * prev;
mylinkage * next;

protected:
friend void set_prev(mylinkage* L, mylinkage* N);
void set_next(mylinkage* L);

public:
mylinkage * succ();
mylinkage * pred();
mylinkage();

};

void mylinkage::set_next(mylinkage* L) { next = L; }
void set_prev(mylinkage * L, mylinkage * N ) { N->prev = L; }
Friends in other classes

It is possible to specify a member function of another class as a friend as follows:

class C {

friend int B::f1();

};

class B {

int f1();
};
It is also possible to specify all the functions in another class as friends, by specifying the entire class as a friend.

class A {

friend class B;

};

Friend functions allow binary operators to be defined which combine private data in a pair of objects. This is particularly powerful when using the operator overloading features of C++. We will return to it when we look at overloading.

 

25. What are the differences between public, private, protected, static, transient, final and volatile?
element                                                                                             Class                    Interface

DataField    Method   Constructor

Modifier                                                                         top level    nested          top level    nested

!                                                                                         (outer)       (inner)         (outer)    (inner)

Final                            yes           yes           no                yes                yes                no              no

Private                        yes          yes           yes               no                  yes                no              yes

Protected                   yes           yes           yes               no                  yes                no              yes

Public                           yes          yes          yes               yes                yes                yes            yes

Static                           yes           yes          no                no                  yes                no              yes

Transient                    yes           no           no                no                  no                 no              no

Volatile                       yes            no           no                no                  no                 no              no

26. What are the different types of errors in php?

Answer: Three are three types of errors:

1.Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although, as you will see, you can change this default behaviour.
2.Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behaviour is to display them to the user when they take place.

27. What is the functionality of the function strstr and stristr?

Answer: strstr() returns part of a given string from the first occurrence of a given substring to the end of the string. For example: strstr(“user@example.com”,”@”) will return “@example.com”.

stristr() is idential to strstr() except that it is case insensitive.

28. What are the differences between PHP 3 and PHP 4 and PHP 5?

Answer: Go read the release notes athttp://php.net.

29. How can we convert asp pages to php pages?

Answer: You can download asp2php front-end application from the site http://asp2php.naken.cc.

30. What is the functionality of the function htmlentities?

Answer: htmlentities — Convert all applicable characters to HTML entities This function is identical tohtmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

31. How can we get second of the current time using date function?

Answer: $second = date(“s”);

 

32. How can we convert the time zones using php?

Answer: <?
echo “Original Time: “. date(“h:i:s”).”\n”;
putenv(“TZ=US/Eastern”);
echo “New Time: “. date(“h:i:s”).”\n”;  ?>

33. What is meant by urlencode and urldocode?

Answer:  urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode(“10.00%”) will return “10%2E00%25”. URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of the given string.

34. What is the difference between the functions unlink and unset?

Answer: unlink() deletes the given file from the file system.
unset() makes a variable undefined.

35. How can we register the variables into a session?

Answer:  We can use the session_register ($ur_session_var) function.

36. How can we get the properties (size, type, width, height) of an image using php image functions?

Answer:  To know the Image type use exif_imagetype () function
To know the Image size use getimagesize () function
To know the image width use imagesx () function
To know the image height use imagesy() function

37. How can we get the browser properties using php?

Answer:  <?php
echo $_SERVER[‘HTTP_USER_AGENT’] . “\n\n”;

$browser = get_browser(null, true);
print_r($browser); ?>

 

38. What is the maximum size of a file that can be uploaded using php and how can we change this?

Answer: You can change maximum size of a file set upload_max_filesize variable in php.ini file

39. How can we increase the execution time of a php script?

Answer: Set max_execution_time variable in php.ini file to your desired time in second.

40. How can we take a backup of a mysql table and how can we restore it.?

Answer:  Create a fullbackup of your database:
shell> mysqldump –tab=/path/to/some/dir –optdb_name
Or:
shell>mysqlhotcopy db_name /path/to/some/dir

The fullbackup file is just a set of SQL statements, so restoring it is very easy:

shell> mysql <backup_sunday_1_PM.sql

41. How can we optimize or increase the speed of a mysql select query?

Answer: In general, when you want to make a slow SELECT … WHERE query faster, the first thing to check is whether you can add an index. All references between different tables should usually be done with indexes. You can use the EXPLAIN statement to determine which indexes are used for a SELECT. Some general tips for speeding up queries on MyISAM tables: A: To help MySQL better optimize queries, use ANALYZE TABLE or run myisamchk –analyze on a table after it has been loaded with data. This updates a value for each index part that indicates the average number of rows that have the same value. (For unique indexes, this is always 1.) MySQL uses this to decide which index to choose when you join two tables based on a non-constant expression. You can check the result from the table analysis by using SHOW INDEX FROM tbl_name and examining the Cardinality value. myisamchk –description –verbose shows index distribution information.

 

42. How many ways can we get the value of current session id?

Answer:  session_id() returns the session id for the current session.

43. How can we destroy the session, how can we unset the variable of a session?

Answer: session_unregister() unregisters a global variable from the current session.
session_unset() frees all session variables.

 

44. How can we destroy the cookie?

Answer:: Set the cookie in past.

45. How many ways we can pass the variable through the navigation between the pages?

Answer: At least 3 ways:
a) Register the variable into the session
b) Pass the variable as a cookie
c) Pass the variable as part of the URL

 

46. What is the difference between ereg_replace() and eregi_replace()?

Answer: eregi_replace() function is identical to ereg_replace() except that this ignores case
distinction when matching alphabetic characters.

47. What are the different functions in sorting an array?

Answer: Sorting functions in PHP:
asort(), arsort(), ksort(), krsort(), uksort(), sort(), natsort(), rsort()

48. How can we know the count/number of elements of an array?

Answer: 2 ways:
a) sizeof($urarray) This function is an alias of count()
b) count($urarray)

Interestingly if u just pass a simple var instead of a an array it will return 1.

49. What is the php predefined variable that tells the What types of images that php supports?

Answer:  $_SERVER[‘HTTP_ACCEPT’]

50. How can I know that a variable is a number or not using a _JavaScript?

Answer:  function IsNumeric(sText) {

var ValidChars = “0123456789.”;
var IsNumber=true;
var Char;
for (i = 0; i < sText.length && IsNumber == true; i++)

{          Char = sText.charAt(i);

if (ValidChars.indexOf(Char) == -1)

{          IsNumber = false;

}

}

return IsNumber;

}

51. List out some tools through which we can draw E-R diagrams for mysql.

Answer: Dbdesigner, conceptdraw etc.

52. How can I retrieve values from one database server and store them in other database server using php?
Answer:  <?php
db_connect($host,$user,$pwd)
{$host_name=$host;

$user=$user;
$pwd=$pwd;
$link1 = mysql_connect($host_name, $user, $pwd);
if (!$link1) {

die(‘Could not connect: ‘ . mysql_error());

}
return($link1);
}$link1 =db_connect(hostname, username, password);

$im=mysql_select_db(“test”) or mysql_error();
$result1=mysql_query(“select * from student”)or mysql_error();
while ($row = mysql_fetch_array($result1)) {

$id=$row[“id”];
$name=$row[“name”];
$roll=$row[“roll”];
}mysql_close($link1);

$link2 = db_connect(hostname, username, password);

$im1=mysql_select_db(“test1″) or die(mysql_error());
//$query1=”insert into student1(‘name’,’roll’,’address’) values($id,$name,$roll)”;
$result1=mysql_query(“insert into student1 values(‘$id’,’$name’,’$roll’)”) or

die(mysql_error());
echo “<br>”.”Executed”;
mysql_close($link2);

?>

53. List out the predefined classes in php?

Answer:
Directory
stdClass
__PHP_Incomplete_Class

exception

php_user_filter

54. How can I make a script that can be bilanguage (supports Eglish, German)?

Answer : <meta http-equiv=”Content-Type” content=”text/html; charset=iso-8859-1″>
You can change charset variable in above line in the script to support bilanguage.

55. What are the difference between abstract class and interface?

Abstract class: abstract classes are the class where one or more methods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not define. The definition of those methods must be in its extending class. Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be define by its implemented class.

56. How can we send mail-using _JavaScript?

Answer:  NO! JavaScript can’t email a form! but, there are alternatives to send the form data to an email address.
Try this:
<form action=”mailto:you@yourdmainhere.com” method=”post”
enctype=”text/plain” >

FirstName:<input type=”text” name=”FirstName”>

Email:<input type=”text” name=”Email”>
<input type=”submit” name=”submit” value=”Submit”>
</form>

57. How can we repair a mysql table?

Answer:
The syntex for repairing a mysql table is
REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended]

This command will repair the table specified if the quick is given the mysql will do a repair of only the index tree if the extended is given it will create index row by row

58. What are the advantages of stored procedures, triggers, indexes?

A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don’t need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side.

Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.

Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.

59. What is the maximum length of a table name, database name, and fieldname in mysql?

Answer:  Database name- 64
Table name -64
Fieldname-64

60. How many values can the SET function of mysql takes?

Answer:  Mysql set can take zero or more values but at the maximum it can take 64 values

61. What are the other commands to know the structure of table using mysql commands except explain command?

Answer:  describe table_name;

62. How many tables will create when we create table, what are they?

What are the MySQL database files stored in system ?

Answer: 3 tables will create when we create table. They are
The `.frm’ file stores the table definition.
The data file has a `.MYD’ (MYData) extension.
The index file has a `.MYI’ (MYIndex) extension,

63. What is the purpose of the following files having extensions 1) frm 2) MYD 3) MYI. What these files contains?

Answer:  In MySql, the default table type is MyISAM.
Each MyISAM table is stored on disk in three files. The files have names that begin
with the table name and have an extension to indicate the file type.
The `.frm’ file stores the table definition.
The data file has a `.MYD’ (MYData) extension.

The index file has a `.MYI’ (MYIndex) extension,

64. What is maximum size of a database in mysql?

Answer:  If the operating system or filesystem places a limit on the number of files in a directory, MySQL is bound by that constraint.

The efficiency of the operating system in handling large numbers of files in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected. The amount of available disk space limits the number of tables. MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 – 1 bytes). With this larger allowed table size, the maximum effective table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits. The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This allows a table to exceed the maximum individual file size. The tablespace can include raw disk partitions, which allows extremely large tables. The maximum tablespace size is 64TB.

The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive. For the most up-to-date information, be sure to check the documentation specific to your operating system. Operating System File-size Limit

Linux 2.2-Intel 32-bit

2GB (LFS: 4GB)

Linux 2.4+ (using ext3 filesystem) 4TB

Solaris 9/10 16TB

NetWare w/NSS filesystem 8TB

Win32 w/ FAT/FAT32

2GB/4GB

Win32 w/ NTFS

2TB (possibly larger)

MacOS X w/ HFS+ 2TB

65. Give the syntax of Grant and Revoke commands?

The generic syntax for grant is as following

> GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY

[password]
now rights can be
a) All privilages
b) combination of create, drop, select, insert, update and delete etc.

we can grant rights on all databse by usingh *.* or some specific database by  database.* or a specific table by database.table_name

username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition password is simply the password of user

The generic syntax for revoke is as following
> REVOKE [rights] on [database/s] FROM [username@hostname] now rights can be as explained above
a) All privilages
b) combination of create, drop, select, insert, update and delete etc.

username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition

66. Explain Normalization concept?

The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).

First Normal Form

The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).

Second Normal Form

Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.

Third Normal Form

I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table

67. How can we find the number of rows in a table using mysql?

Answer:  Use this for mysql
>SELECT COUNT(*) FROM table_name;
but if u r particular about no of rows with some special result
do this
>SELECT [colms],COUNT(*) FROM table_name [where u put conditions];

68. How can we find the number of rows in a result set using php?

Answer:  for PHP
$result = mysql_query($any_valid_sql, $database_link);
$num_rows = mysql_num_rows($result);
echo “$num_rows rows found”;

69. How many ways we can we find the current date using mysql?

Answer:   SELECT CURDATE();
CURRENT_DATE() = CURDATE()
for time use
SELECT CURTIME();
CURRENT_TIME() = CURTIME()

70. What are the advantages and disadvantages of CASCADE STYLE SHEETS?

External Style Sheets
Advantages
Can control styles for multiple documents at once Classes can be created for use on multiple HTML element types in many documents
Selector and grouping methods can be used to apply styles under complex contexts
Disadvantages
An extra download is required to import style information for each document The rendering of the document may be delayed until the external style sheet is loaded Becomes slightly unwieldy for small quantities of style definitions Embedded Style Sheets
Advantages
Classes can be created for use on multiple tag types in the document Selector and grouping methods can be used to apply styles under complex contexts No additional downloads necessary to receive style information
Disadvantages
This method can not control styles for multiple documents at once Inline Styles
Advantages
Useful for small quantities of style definitions Can override other style specification methods at the local level so only exceptions
need to be listed in conjunction with other style methods
Disadvantages
Does not distance style information from content (a main goal of SGML/HTML) Can not control styles for multiple documents at once
Author can not create or control classes of elements to control multiple element types within the document Selector grouping methods can not be used to create complex element addressing scenarios

71. What type of inheritance that php supports?

Answer:  In PHP an extended class is always dependent on a single base class, that is, multiple inheritance is not supported. Classes are extended using the keyword ‘extends’.
Usage:

<?php

Class Namd_Cart extend Cart{

var$owner;

functionset_owner ($name) {

$this->owner= $name;

}

}?>

72. How can increase the performance of mysql select query?

The structure of table view buyers is as follows

+—————-+————-+——+—–+———+—————-+
| Field | Type | Null | Key | Default | Extra |
+—————-+————-+——+—–+———+—————-+
| user_pri_id | int(15) | | PRI | NULL | auto_increment |
| userid | varchar(10) | YES | | NULL | |
+—————-+————-+——+—–+———+—————-+

the value of user_pri_id the last row 2345 then What will happen in the following conditions

Condition1: Delete all the rows and insert another row then What is the starting value for this auto incremented field user_pri_id ,
Condition2: Delete the last row(having the field value 2345) and insert another row then What is the value for this auto incremented
field user_pri_id

Answer:

In general, when you want to make a slow SELECT … WHERE query faster, the first thing to check is whether you can add an index. All references between different tables should usually be done with indexes. You can use the EXPLAIN statement to determine which indexes are used for a SELECT. See section 7.4.5 How MySQL Uses Indexes and section 7.2.1 EXPLAIN Syntax (Get Information About a SELECT).

Some general tips for speeding up queries on MyISAM tables:

To help MySQL optimize queries better, use ANALYZE TABLE or run myisamchk –analyze on a table after it has been loaded with data. This updates a value for each index part that indicates the average number of rows that have the same value. (For unique indexes, this is always 1.) MySQL will use this to decide which index to choose when you join two tables based on a non-constant expression. You can check the result from the table analysis by using SHOW INDEX FROM tbl_name and examining the Cardinality value. myisamchk –description –verbose shows index distribution information.

To sort an index and data according to an index, use myisamchk –sort-index –sort- records=1 (if you want to sort on index 1). This is a good way to make queries faster if you have a unique index from which you want to read all records in order

according to the index. Note that the first time you sort a large table this way, it may take a long time.

In both cases let the value for auto increment field be n then next row will have value n+1 i.e. 2346

73. What are the advantages/disadvantages of mysql and php?

Answer:  Both of them are open source software (so free of cost), support cross platform. php is faster then ASP and JSP.

74. What is the difference between GROUP BY and ORDER BY in Sql?

Answer: To sort a result, use an ORDER BYclause.

The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then use this temporary table to discover groups and apply aggregate functions (if any).

ORDER BY [col1],[col2],…,[coln]; Tels DBMS according to what columns it should sort the result. If two rows will hawe the same value in col1 it will try to sort them according to col2 and so on.

GROUP BY [col1],[col2],…,[coln]; Tels DBMS to group results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average

 

75. What is the difference between char and varchar data types?

Answer:  char(M) M bytes 0<=M<=255

varchar(M) L+1 bytes where L<=M & 0<=M<=255

i.e.; char data type allocate memory statically

and varchar data type allocate memory dynamically

76. What is the functionality of md5 function in php?

Answer:   string md5(string)

Calculate the md5 hash of a string. The hash is a 32-character hexadecimal number. We can use it to generate keys, which we use to identify users etc. If we add random no techniques to it the md5 generated now will be totally different for the same string we are using..

 

77. How can I load data from a text file into a table?

Answer:  The mysql provides a LOAD DATA INFILE syntax. U can load data from a file.
Gr8 tool but u need to make sure that
a) data is delimited
b) u match the colms and data correctly dont use w/out first learning the syntax

78. How can we know the number of days between two given dates using mysql?

Answer: select DIFFDATE( NOW(), ‘yyyy-mm-dd’ );

79. How can we know the number of days between two given dates using php?

Answer:  <?php
$tomorrow = mktime(0, 0, 0, date(“m”) , date(“d”)+1, date(“Y”));
$lastmonth = mktime(0, 0, 0, date(“m”)-1, date(“d”),date(“Y”));
echo ($tomorrow-$lastmonth)/86400; ?>

80. How can we change the name of a column of a table?

Answer:  MySQL query to rename table: RENAME TABLEtbl_name TOnew_tbl_name [,tbl_name2 TOnew_tbl_name2] …

or,

ALTER TABLE tableName CHANGE OldName newName.

81. How can we change the name and data type of a column of a table?

Answer:   ALTER [IGNORE] TABLEtbl_name alter_specification[, alter_specification] | CHANGE [COLUMN] old_col_name column_definition [FIRST|AFTERcol_name]

82. What are the differences between drop a table and truncate a table?

Answer:  Delete a Table or DatabaseTo delete a table (the table structure, attributes, and indexes will also be deleted).
What if we only want to get rid of the data inside a table, and not the table itself?
Use the TRUNCATE TABLE command (deletes only the data inside the table).

83. When you want to show some part of a text displayed on an HTML page in red font color, what different possibilities are there to do this? What are the advantages/disadvantages of these methods?

Answer:   Using Html font color tag:
<font color=RED> I am Amin </font>
Using tag in CSS:
STRONG {color:red}
So when we use the <STRONG> tag:

I am <STRONG>Amin</STRONG> about this.
Using Class in CSS:
.colorclass
{color:#FF3399;

font-weight:900;

}I am <SPAN CLASS=”colorclass”>Amin</SPAN>

If we use html the modification will be trouble some because we have to change the code of the page. But when we use CSS then it will be easy to change the CSS file and we can get the desired out put.

84. When viewing an HTML page in a Browser, the Browser often keeps this page in its cache. What can be possible advantages/disadvantages of page caching? How can you prevent caching of a certain page (please give several alternate solutions)?

Answer:  When you use the <HTTP-EQUIV=”PRAGMA” CONTENT=”NO-CACHE”> metatag in the header section at the beginning of an HTML Web page, the Web page may still be cached in the Temporary Internet Files folder. A page that Internet Explorer is browsing is not cached until half of the 64 KB
> buffer is filled. Usually, metatags are inserted in the header section of an
> HTML document, which appears at the beginning of the document. When the HTML code is parsed, it is read from top to bottom. When the <HTTP-EQUIV=”PRAGMA” CONTENT=”NO-CACHE”> metatag is read, Internet Explorer looks for the existence of the page in cache at that exact moment. If it is there, it is removed. To properly prevent the Web page from appearing in the cache, place another header section at the end of the HTML ocument. For example:

</BODY>
<HEAD>
<META HTTP-EQUIV=”PRAGMA” CONTENT=”NO-CACHE”>
</HEAD>
</HTML>

85. What are the different methods of passing data or information between two calls of a web page? What are the advantages/disadvantages of these methods?

86. An Apache web server is running on a Linux system. Suddenly, the web server delivers the pages very slow. How could you find out possible reasons for that (when using system commands, please specify their names)?

 

87. What are the different ways to login to a remote server? Explain the means, advantages and disadvantages?

Answer:  There is at least 3 ways to logon to a remote server: Use ssh or telnet if you concern with security You can also use rlogin to logon to a remote server.

88. Please give a regular _expression (preferably Perl/PREG style), which can be used to identify the URL from within a HTML link tag. Example: The regular _expression should match the tag <A HREF=”http://www.yoursite.com/&#8221; and give the URL (“http://www.yoursite.com/&#8221;) as a return result. Tags should also be matched if they contain other attributes than the HREF attribute.

Answer: $regexp = “/[http]+[0-9A-Za-z_:\/\.]+[^\”]/”;
$str = “<a HREF=\”http://www.yoursite.com/\””;
preg_match($regexp,$str,$arr);
echo $arr[0];

89. A select query over a large table runs very slow because of the growing number of entries in that table. What different measures could be taken to improve speed?

Answer: In general, when you want to make a slow SELECT … WHERE query faster, the first thing to check is whether you can add an index. All references between different tables should usually be done with indexes. You can use the EXPLAIN statement to determine which indexes are used for a SELECT. Some general tips for speeding up queries on MyISAM tables: A: To help MySQL better optimize queries, use ANALYZE TABLE or run myisamchk –analyze on a table after it has been loaded with data. This updates a value for each index part that indicates the average number of rows that have the same value. (For unique indexes, this is always 1.) MySQL uses this to decide which index to choose when you join two tables based on a non-constant expression. You can check the result from the table analysis by using SHOW INDEX FROM tbl_name and examining the Cardinality value. myisamchk –description –verbose shows index distribution information.

90. A company wants to store their invoices in a database. They already have their customers and articles in that database. Both customer and article are each identified by an unique integer value. Please create the SQL statements for creating the necessary table(s) for storing the invoices in a MySQL database. An invoice should hold information like invoice number, customer, date, article(s) and quantity etc.

Ans: CREATE TABLE invoice (
id int(11) NOT NULL default ‘0’,
invoceNo int(11) NOT NULL default ‘0’,
customer_id varchar(20) NOT NULL default ‘0’,
article_id varchar(20) NOT NULL default ‘0’,
date varchar(20) NOT NULL default ‘0’,
quantity int(11) NOT NULL default ‘0’,

PRIMARY KEY (id)

) TYPE=MyISAM;

91. For the database from the previous question, please give an SQL query which returns the invoice number of all invoices which contain the article with the number “1234”. The query should be able to run under a MySQL 4.0 database.

Answer:   Select invoceNo from invoice where article_id=1234;

92. How would you backup and restore a big MySQL database? What are the advantages of the approach which you have taken over the others?

Use the mysqldump command.

If you have Telnet/SSH access to your MySQL server, log in and issue the following command for each database you want to back up:

shell> mysqldump -u user -ppassword –opt -full database_name > backupfile.sql

Then move the resulting file(s) to your preferred backup areas. If you require more information on the mysqldump command, then simply check out this URL:www.mysql.com/documentation/mysql

Copy all the relevant table files.

If the server isn’t updating anything (or you’ve deliberately killed mysqld for this purpose) then you can copy all the files with the following extensions in your MySQL data directory:

*.frm
*.myd
*.myi

Make sure you restart the MySQL daemon once you finish copying and downloading the files to your preferred backup areas.

TIP: once you’ve completed the backup, restart MySQL with the –log-update switch. This will allow you to keep track of all modifications done in the MySQL tables since your last ‘dump’.

To restore your dumps, you should either restore to an existing database or create a new database using
shell> mysqladmin create database_name
then issue the following command :
shell> mysql -u user -ppassword database_name < backup-file.sql

If you don’t have access to Telnet/SSH and you’re unable to do backups using the methods described above, you should ask your host if it is possible for them to do a backup for you and put the backups in a separate directory so that you can easily FTP your backups to your selected backup areas. Otherwise, if you have access to phpMyAdmin, you can use the following procedure:

Access phpMyAdmin, and select the database you wish to ‘dump’ (backup). Scroll down and you will see a bulleted point saying: “View dump (schema) of database” along with some radio and check boxes. Choose ‘Structure and data’, then click on ‘Add Drop Table’ and ‘Send’ and click ‘Go’. This will save the ‘dump’ to your hard drive.

To restore a dump using phpMyAdmin, simply insert the file in the correct place once you have chosen the correct database by doing the following: Choose the database you will insert your data into, or create a new database.

Insert the appropriate SQL queries you already have, or just paste the name of the .sql file you have on your hard drive into the text box under ‘Location of the textfile’, and fire away!

Tip : use a crontab job to schedule backups periodically. The advantages of this approach is the backup is only a file consisting of SQL query. So that needs minimum spaces to backup a large database.

93. Create a PHP web script with the following attributes: on start, three HTML form elements are shown: an string input field, a checkbox field, a dropdown/pull down list with 5 elements and a submit button. On submission, the form should be redisplayed (while remaining all options/inputs as the user has selected/entered them). Additionally, the selections/inputs of the user should be displayed in text. Please solve this without the use of any external libraries.

Ans:   <?
$name=$_POST[‘txtName’]; //Value of text field
$chkState=$_POST[‘chkState’]; // Value of check box
$sltItem=$_POST[‘sltItem’]; // Value of the List box
?>
<form name=”form1″ method=”post” action=””>

<table width=”100%” border=”0″>

<tr>

<td> <input name=”txtName” type=”text” id=”txtName” value=<? echo $name

?>></td>

</tr> <tr>

<td><input name=”chkState” type=”checkbox” <? if($chkState==’on’) echo

“checked” ?> ></td>

</tr><tr>

<td><div align=”right”></div>

<select name=”sltItem” id=”sltItem”>
<?
$arr=array(“BD”,”AU”,”USA”,”UK”,”JP”); //Array of the Items os

list box

for($i=0;$i<5;$i++){ // 5 items are taken as sample
if($sltItem==$i)
echo” <option value=$i selected >$arr[$i] </option>”;
else
echo” <option value=$i>$arr[$i] </option>”;
}

?>

</select></td>

</tr><tr>

<td><input type=”submit” name=”Submit” value=”Submit”>

</td>

</tr> </table>

</form>

94. What is meant by MIME?

Answer:  Multipurpose Internet Mail Extensions.

WWW’s ability to recognise and handle files of different types is largely dependent on the use of the MIME (Multipurpose Internet Mail Extensions) standard. The standard provides for a system of registration of file types with information about the applications needed to process them. This information is incorporated into Web server and browser software, and enables the automatic recognition and display of registered file types. …

95. What is meant by PEAR in php?

Answer:  PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide: A structured library of open-sourced code for PHP users A system for code distribution and package maintenance A standard style for code written in PHP The PHP Foundation Classes (PFC), The PHP Extension Community Library (PECL), A web site, mailing lists and download mirrors to support the PHP/PEAR community

PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

http://pear.php.net/manual/en/introduction.php

96. How can I use the COM components in php?

Answer:  The COM class provides a framework to integrate (D)COM components into your PHP scripts.

stringCOM::COM ( string module_name [, string server_name [, int codepage]]) COM class constructor. Parameters:

module_name name or class-id of the requested component. server_name name of the DCOM server from which the component should be fetched. IfNULL, localhost is assumed. To allow DCOMcom.allow_dcom has to be set toTRUE inphp.ini. codepage specifies the codepage that is used to convert php-strings to unicode-strings and vice versa. Possible values areCP_ACP, CP_MACCP, CP_OEMCP, CP_SYMBOL, CP_THREAD_ACP, CP_UTF7and CP_UTF8.

Usage:

<?php

// starting word

$word = newCOM(“word.application”) or die(“Unable to instanciate

Word”);

echo “Loaded Word, version {$word->Version}\n”;

//bring it to front

$word->Visible= 1;

//open an empty document

$word->Documents->Add();

//do some weird stuff

$word->Selection->TypeText(“This is a test…”);

$word->Documents[1]->SaveAs(“Useless test.doc”);

//closing word

$word->Quit();

//free the object

$word->Release();
$word= null;
?>

97. How can I load the dll’s dynamically?

 

98. How many ways we can give the output to a browser?

Answer:  HTML output PHP, ASP, JSP, Servlet Function Script Language output Function Different Type of embedded Package to output to a browser

99. How can we know that a session is started or not?

Answer:  a session starts by session_start()function.
this session_start() is always declared in header portion.it always declares first.then
we write session_register().

100. What is the default session time in php and how can I change it?

Answer:   The default session time in php is until closing of browser

101. What changes I have to done in php.ini file for file uploading?

Answer:  Make the following Line uncomment like: ; Whether to allow HTTP file uploads. file_uploads = On ; Temporary directory for HTTP uploaded files (will use system default if not ; specified).
upload_tmp_dir = C:\apache2triad\temp ; Maximum allowed size for uploaded files.

upload_max_filesize = 2M

102. What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?

Answer:  mysql_fetch_array — Fetch a result row as an associative array, a numeric array, or both.

mysql_fetch_object ( resource result ) Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows

mysql_fetch_row() fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.

103. How can I set a cron and how can I execute it in Unix, Linux, and windows?

Answer:   Cron is very simply a Linux module that allows you to run commands at predetermined times or intervals. In Windows, it’s called Scheduled Tasks. The name Cron is in fact derived from the same word from which we get the word chronology, which means order of time. The easiest way to use crontab is via the crontab command.

# crontab –e

This command ‘edits’ the crontab. Upon employing this command, you will be able to enter the commands that you wish to run. My version of Linux uses the text editor vi. You can find information on using vi here. The syntax of this file is very important – if you get it wrong, your crontab will not  function properly. The syntax of the file should be as follows: minutes hours day_of_month month day_of_week command All the variables, with the exception of the command itself, are numerical constants. In addition to an asterisk (*), which is a wildcard that allows any value, the ranges permitted for each field are as follows:

Minutes: 0-59
Hours: 0-23
Day_of_month: 1-31
Month: 1-12
Weekday: 0-6

We can also include multiple values for each entry, simply by separating each value with a comma. command can be any shell command and, as we will see momentarily, can also be used to execute a Web document such as a PHP file. So, if we want to run a script every Tuesday morning at 8:15 AM, our mycronjob file will contain the following content on a single line:

15 8 * * 2 /path/to/scriptname

This all seems simple enough, right? Not so fast! If you try to run a PHP script in this manner, nothing will happen (barring very special configurations that have PHP compiled as an executable, as opposed to an Apache module). The reason is that, in order for PHP to be parsed, it needs to be passed through Apache. In other words, the page needs to be called via a browser or other means of retrieving Web content.

For our purposes, I’ll assume that your server configuration includes wget, as is the case with most default configurations. To test your configuration, log in to shell. If you’re using an RPM-based system (e.g. Redhat or Mandrake), type the following:

# wget –help

If you are greeted with a wget package identification, it is installed in your system.

You could execute the PHP by invoking wget on the URL to the page, like so:

# wget http://www.example.com/file.php

Now, let’s go back to the mailstock.php file we created in the first part of this article. We saved it in our document root, so it should be accessible via the Internet. Remember that we wanted it to run at 4PM Eastern time, and send you your precious closing bell report? Since I’m located in the Eastern timezone, we can go ahead and set up our crontab to use 4:00, but if you live elsewhere, you might have to compensate for the time difference when setting this value.

This is what my crontab will look like:

0 4 * * 1,2,3,4,5 wget http://www.example.com/mailstock.php

104. Steps for the payment gateway processing?

Ans:   An online payment gateway is the interface between your merchant account and your Web site. The online payment gateway allows you to immediately verify credit card transactions and authorize funds on a customer’s credit card directly from your Web site. It then passes the transaction off to your merchant bank for processing, commonly referred to as transaction batching

105. How many ways I can register the variables into session?

Answer:   session_register();
$_SESSION[];
$HTTP_SESSION_VARS[];

106. Explain different types of errors in php (i.e. arguments in error reporting function)?

Answer:  Three are three types of errors:
1.Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although, as you will see, you can change this default behaviour.
2.Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behaviour is to display them to the user when they take place.

107. How many ways I can redirect a php page?

Answer;   Here are the possible ways of php page redirection. Using Java script:

<?php

functionredirect( $filename) {

if (!headers_sent())

header(‘Location: ‘.$filename);

else {

echo ‘<script type=”text/javascript”>’;
echo ‘window.location.href=”‘.$filename.'”;’;
echo ‘</script>’;
echo ‘<noscript>’;
echo ‘<meta http-equiv=”refresh” content=”0;url=’.$filename.'” />’;
echo ‘</noscript>’;

}

}redirect(‘http://maosjb.com&#8217;);

?>

Using php function:

Header(“Location:http://maosjb.com “);

108. List out different arguments in php header function?

Answer:  voidheader ( string string [, bool replace [, int http_response_code]])

109. What type of headers have to add in the mail function in which file a attached?

Answer:  $boundary = ‘—–=’ . md5( uniqid ( rand() ) );
$headers = “From: \”Me\”<me@here.com>\n”;
$headers .= “MIME-Version: 1.0\n”;
$headers .= “Content-Type: multipart/mixed; boundary=\”$boundary\””;

110. What is the difference between <?php ?> and <? ?> And which can be preferable?

Answer:  If functionality is same but <? Is the short tag of <?php. Using short tags should be avoided when developing applications or libraries that are meant for redistribution, or deployment on PHP servers, which are not under your control, because short tags may not be supported on the target server. For portable, redistributable code, be sure not to use short tags.

111. What are the differences between php3 and php4 versions?

Answer:  As has already been mentioned by many PHP4 has native support for sessions and the much touted XML. While this makes PHP a competitor in the Application server languages arena, there is another core aspect to PHP4. It is faster.

PHP3 used to parse line by line, while PHP acts like a compiler. This along with the ZEND optimizer makes PHP4 almost always faster than PHP3. I’m not sure about support for COM, it has caught my attention only in PHP4. If it was present in PHP3 I was not aware of it. Plus PHP4 can run as an Apache module, again this could have come in the late versions of PHP3.

112. What are the differences between include() and include_once() functions?

Answer: include_once() will use the specified file only once. include and require will use the specified file as many time we want. If include_once() is used before with same name, it can not done again

113. Describe the importance of DATA BASE ABSTRACTION LAYERS in php and database connection?

Answer: Please visit to know about Database abstraction layers
http://www.oracle.com/technology/pub/articles/deployphp/schlitt_deployphp.html

114. Explain mysql optimization?

Answer:   Optimization is a complex task because ultimately it requires understanding of the entire system. Although it may be possible to perform some local optimizations with little knowledge of your system or application, the more optimal you want your system to become, the more you will have to know about it. The most important factor in making a system fast is the basic design. You also need to know what kinds of things your system will be doing, and what your bottlenecks are.

See more at:

http://www.serveriai.lt/manual/mysql/manual_MySQL_Optimisation.html

115. What is the difference between using copy() and move() function in php file uploading?

copy ( string source, string dest)

Makes a copy of the filesource todest. ReturnsTRUE on success orFALSE on failure.
Usage:

<?php

if (!copy($file,$file.’.bak’)) {

echo “failed to copy $file…<br />\n”;

}?>

move_uploaded_file ( string filename, string destination)

This function checks to ensure that the file designated byfilename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given bydestination.

Iffilename is not a valid upload file, then no action will occur, and

move_uploaded_file() will returnFALSE.

Iffilename is a valid upload file, but cannot be moved for some reason, no action will occur, and move_uploaded_file() will returnFALSE. Additionally, a warning will be issued.

116. What is the difference between Reply-to and Return-path in the headers of a mail function?

Answer:  Reply-to: Reply-to is where to delivery the reply of the mail.

Return-path: Return path is when there is a mail delivery failure occurs then where

to delivery the failure notification.

117. Explain about Type Juggling in php?

Answer:  PHP does not require (or support) explicit type definition in variable declaration; a variable’s type is determined by the context in which that variable is used. That is to say, if you assign a string value to variable $var, $var becomes a string. If you then assign an integer value to $var, it becomes an integer.

An example of PHP’s automatic type conversion is the addition operator ‘+’. If any of the operands is a float, then all operands are evaluated as floats, and the result will be a float. Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does NOT change the types of the operands themselves; the only change is in how the operands are evaluated.

<?php
$foo = “0”; // $foo is string (ASCII 48)
<!– bad example, no real operator (must be used with variable, modifies it too)
$foo++;

// $foo is the string “1” (ASCII 49)
–>
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + “10 Little Piggies”; // $foo is integer (15)
$foo = 5 + “10 Small Pigs”; // $foo is integer (15)
<!–

TODO: explain ++/- – behaviour with strings

examples:

++’001′ = ‘002’ ++’abc’ = ‘abd’ ++’xyz’ = ‘xza’ ++’9.9′ = ‘9.0’

++’-3′ = ‘-4’

– -‘9’ = 8 (integer!)
– -‘5.5’ = ‘5.5’
– -‘-9′ = -10 (integer)
– -’09’ = 8 (integer)
– -‘abc’ = ‘abc’

–>

?>
If the last two examples above seem odd, see String conversion to numbers. If you wish to change the type of a variable, see settype().

If you would like to test any of the examples in this section, you can use the var_dump() function.

Note: The behavior of an automatic conversion to array is currently undefined.

<?php
$a = “1”; // $a is a string
$a[0] = “f”; // What about string offsets? What happens?
?>

Since PHP (for historical reasons) supports indexing into strings via offsets using the same syntax as array indexing, the example above leads to a problem: should $a become an array with its first element being “f”, or should “f” become the first character of the string $a?

The current versions of PHP interpret the second assignment as a string offset identification, so $a becomes “f”, the result of this automatic conversion however should be considered undefined. PHP 4 introduced the new curly bracket syntax to access characters in string, use this syntax instead of the one presented above:

<?php
$a = “abc”; // $a is a string
$a{1} = “f”; // $a is now “afc”
?>

118. How can I get the only name of the current executing file?

<?php   $curfilename = __FILE__; //current file name with full path
$pieces = explode(“\\”, $curfilename);
$onlyfilenamewithext = $pieces[count($pieces)-1]; //current file name with extension
only
$temp = explode(“.”,$onlyfilenamewithext);
$onlyfilename = $temp[0]; //current file name without extension
echo $onlyfilename;  ?>

 

 

119. How can I embed a java programme in php file and what changes have to be done in php.ini file?

There are two possible ways to bridge PHP and Java: you can either integrate PHP into a Java Servlet environment, which is the more stable and efficient solution, or integrate Java support into PHP. The former is provided by a SAPI module that interfaces with the
Servlet server, the latter by this Java extension.

The Java extension provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process.  Example Code:

<?php   // get instance of Java class java.lang.System in PHP

$system = new Java(‘java.lang.System’);

// demonstrate property access

echo ‘Java version=’ .$system->getProperty(‘java.version’) . ‘<br />’;
echo ‘Java vendor=’ .$system->getProperty(‘java.vendor’) . ‘<br />’;
echo’OS=’ .$system->getProperty(‘os.name’) .’ ‘ .

$system->getProperty(‘os.version’) . ‘ on ‘ .

$system->getProperty(‘os.arch’) . ‘ <br />’;

// java.util.Date example

$formatter = new Java(‘java.text.SimpleDateFormat’,

“EEEE,MMMM dd,yyyy ‘at’ h:mm:ss azzzz”);

echo$formatter->format(newJava(‘java.util.Date’));  ?>

The behaviour of these functions is affected by settings inphp.ini.

Table 1. Java configuration options

Name Default Changeable
Java.class.path NULL PHP_INI_ALL
Java.home NULL PHP_INI_ALL
Java.library.path NULL PHP_INI_ALL
Java.library JAVALIB PHP_INI_ALL

120. How can I find what type of images that the php version supports?

Answer: Using Imagetypes() function we can know
Usage:

<?php  if (imagetypes() &IMG_PNG) {

echo “PNG Support is enabled”;

}?>

121. The table tbl_sites contains the following data.

—————————————————–

Userid  sitename           country

——————————————————

1          sureshbabu         indian

2          phpprogrammer andhra

3          php.net              usa

4          phptalk.com       germany

5          mysql.com         usa

6          sureshbabu         anada

7          phpbuddy.com   pakistan

8.         phptalk.com       austria

9.         phpfreaks.com   sourthafrica

10.        phpsupport.net   russia

11.        sureshbabu         australia

12.        sureshbabu         nepal

13.        phptalk.com       italy

Write a select query that will displayed the duplicated site name and how many times it is duplicated?

Answer: SELECT sitename, COUNT(sitename) AS NumOccurrences FROM tbl_sites GROUP BY sitemail HAVING ( COUNT(sitemail) > 1 )

Or

SELECT sitename FROM tbl_sites GROUP BY sitename HAVING ( COUNT(sitename) = 1 )

122. How can we send mail using JavaScript?

Answer:   No. You can’t send mail using Javascript. But you can execute a client side email client to send the email using mailto: code. Using clientside email client
function myfunction(form)
{tdata=document.myform.tbox1.value;

location=”mailto:mailid@domain.com?subject=”+tdata+”/MYFORM”;

return true; }

Sources :
DEVFYI – Developer Resource – FYI
TechGuider – techguider

How To Read the Entire File into a Single String?

If you have a file, and you want to read the entire file into a single string, you can use the file_get_contents() function. It opens the specified file, reads all characters in the file, and returns them in a single string. Here is a PHP script example on how to file_get_contents():

<?php   $file = file_get_contents(“/windows/system32/drivers/etc/services”);

print(“Size of the file: “.strlen($file).”\n”); ?>
This script will print:
Size of the file: 7116

Explain the ternary conditional operator in PHP?

How To Turn On the Session Support?

The session support can be turned on automatically at the site level, or manually in each PHP page script:

• Turning on session support automatically at the site level: Set session.auto_start = 1 in php.ini.

• Turning on session support manually in each page script: Call session_start() funtion.

How to store the uploaded file to the final location?

move_uploaded_file ( string filename, string destination)

This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination. If filename is not a valid upload file, then no action will occur, and move_uploaded_file() will return FALSE. If filename is a valid upload file, but cannot be moved for some reason, no action will occur, and move_uploaded_file() will return FALSE. Additionally, a warning will be issued.

What changes I have to do in php.ini file for file uploading?

Make the following line uncomment like:; Whether to allow HTTP file uploads.
file_uploads = On;

Temporary directory for HTTP uploaded files (will use system default if not; specified).
upload_tmp_dir = C:\apache2triad\temp;

Maximum allowed size for uploaded files.
upload_max_filesize = 2M

What’s the difference between accessing a class method via -> and via ::?

:: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.

How can I know that a variable is a number or not using a JavaScript?

bool is_numeric( mixed var) Returns TRUE if var is a number or a numeric string, FALSE otherwise.

Definition and Usage The isNaN() function is used to check if a value is not a number.

Syntax

isNaN(number)  Parameter Description number Required. The value to be tested

How to set cookies?

setcookie(‘variable’,’value’,’time’) ;variable – name of the cookie variable

value – value of the cookie variable
time – expiry time
Example: setcookie(‘Test’,$i,time()+3600);

Test – cookie variable name
$i – value of the variable ‘Test’
time()+3600 – denotes that the cookie will expire after an one hour

 

How to reset/destroy a cookie

Reset a cookie by specifying expire time in the past:

Example: setcookie(‘Test’,$i,time()-3600); // already expired time

Reset a cookie by specifying its name only

Example: setcookie(‘Test’);

What is the difference between htmlentities() and htmlspecialchars()?

htmlspecialchars() – Convert some special characters to HTML entities (Only the most widely used)
htmlentities() – Convert ALL special characters to HTML entities

What are encryption functions in PHP?

CRYPT()

MD5()

What are the functions for IMAP?

imap_body – Read the message body
imap_check – Check current mailbox
imap_delete – Mark a message for deletion from current mailbox
imap_mail – Send an email message

What is the difference between PHP4 and PHP5?

PHP4 cannot support oops concepts and Zend engine 1 is used.

PHP5 supports oops concepts and Zend engine 2 is used.
Error supporting is increased in PHP5.
XML and SQLLite will is increased in PHP5.

If we login more than one browser windows at the same time with same user and after that we close one window, then is the session is exist to other windows or not? And if yes then why? If no then why?

Session depends on browser. If browser is closed then session is lost. The session data will be deleted after session time out. If connection is lost and you recreate connection, then session will continue in the browser.

How can we know the number of days between two given dates using MySQL?

Use DATEDIFF()    SELECT DATEDIFF(NOW(),’2006-07-01′);

Will comparison of string “10” and integer 11 work in PHP?

Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.

What is the value for this auto incremented field user_pri_id?

In both conditions, the value of this auto incremented field user_pri_id is 2346.

What’s the difference between md5(), crc32() and sha1() crypto on PHP?

The major difference is the length of the hash generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value, and md5() returns a 160 bit value. This is important when avoiding collisions.

What’s the output of the ucwords function in this example?

$formatted = ucwords(“FYICENTER IS COLLECTION OF INTERVIEWQUESTIONS”);
print $formatted;
What will be printed is FYICENTER IS COLLECTION OF INTERVIEW QUESTIONS.
ucwords() makes every first letter of every word capital, but it does not lower-case anything else. To avoid this, and get a properly formatted string, it’s worth using strtolower() first.

I am writing an application in PHP that outputs a printable version of driving directions. It contains some long sentences, and I am a neat freak, and would like to make sure that no line exceeds 50 characters. How do I accomplish that with PHP?

On large strings that need to be formatted according to some length specifications, use wordwrap() or chunk_split().

For printing out strings, there are echo, print and printf. Explain the differences.

echo is the most primitive of them, and just outputs the contents following the construct to the screen. print is also a construct (so parentheses are optional when calling it), but it returns TRUE on successful output and FALSE if it was unable to print out the string. However, you can pass multiple parameters to echo, like:

<?php echo ‘Welcome ‘, ‘to’, ‘ ‘, ‘fyicenter!’; ?>

and it will output the string “Welcome to fyicenter!” print does not take multiple parameters. It is also generally argued that echo is faster, but usually the speed advantage is negligible, and might not be there for future versions of PHP. printf is a function, not a
construct, and allows such advantages as formatted output, but it’s the slowest way to print out data out of echo, print and printf.

How can we submit form without a submit button?

We can use a simple JavaScript code linked to an event trigger of any form field. In the JavaScript code, we can call the document.form.submit() function to submit the form. For example:

<input type=button value=”Save” onClick=”document.form.submit()”>

What is the difference between characters 23 and \x23?

The first one is octal 23, the second is hex 23.

How come the code works, but doesn’t for two-dimensional array of mine?

Any time you have an array with more than one dimension, complex parsing syntax is required. print “Contents: {$arr[1][2]}” would’ve worked.

Would you initialize your strings with single quotes or double quotes?

Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.

Why doesn’t the following code print the newline properly? <?php $str = ‘Hello, there.\nHow are you?\nThanks for visiting fyicenter’; print $str; ?>

Because inside the single quotes the \n character is not interpreted as newline, just as a sequence of two characters – \ and n.

What’s the special meaning of __sleep and __wakeup?

__sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.

How do you call a constructor for a parent class?

parent::constructor($value)

Are objects passed by value or by reference?

Everything is passed by value.

How To Protect Special Characters in Query String?

If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below shows how to use urlencode():

<?php print(“<html>”);
print(“<p>Please click the links below”
.” to submit comments about FYICenter.com:</p>”);
$comment = ‘I want to say: “It\’s a good site! :->”‘;
$comment = urlencode($comment);
print(“<p>”
.”<a href=\”processing_forms.php?name=Guest&comment=$comment\”>”
.”It’s an excellent site!</a></p>”);
$comment = ‘This visitor said: “It\’s an average site! :-(“‘;
$comment = urlencode($comment);
print(“<p>”

.'<a href=”processing_forms.php?’.$comment.'”>’
.”It’s an average site.</a></p>”);
print(“</html>”); ?>

Write a select query that will be displayed the duplicated site name and how many times it is duplicated?

SELECT sitename, COUNT(*) AS NumOccurrences FROM tbl_sites GROUP BY sitename HAVING COUNT(*) > 1

If the variable $a is equal to 5 and variable $b is equal to character a, what’s the value of $$b?

5, it’s a reference to existing variable.

How do I find out the number of parameters passed into function9. ?

func_num_args() function returns the number of parameters passed in.

When are you supposed to use endif to end the conditional statement?

When the original if was followed by : and then the code block without braces.

How do you pass a variable by value?

Just like in C++, put an ampersand in front of it, like $a = &$b

I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem?

PHP Interpreter treats numbers beginning with 0 as octal. Look at the similar PHP interview questions for more numeric problems.

How To Get the Uploaded File Information in the Receiving Script?

Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them. This receiving PHP script can get the uploaded file information through the predefined array called $_FILES. Uploaded file information is organized in $_FILES as a two-dimensional array as:

$_FILES[$fieldName][‘name’] – The Original file name on the browser system.

$_FILES[$fieldName][‘type’] – The file type determined by the browser.

$_FILES[$fieldName][‘size’] – The Number of bytes of the file content.

$_FILES[$fieldName][‘tmp_name’] – The temporary filename of the file in which the uploaded file was stored on the server.

$_FILES[$fieldName][‘error’] – The error code associated with this file upload.

The $fieldName is the name used in the <INPUT TYPE=FILE, NAME=fieldName>.

How do you define a constant?

Via define() directive, like define (“MYCONSTANT”, 100);

What does a special set of tags do in PHP?

What does a special set of tags <?= and ?> do in PHP?

The output is displayed directly to the browser.

What Is a Persistent Cookie?

A persistent cookie is a cookie which is stored in a cookie file permanently on the browser’s computer. By default, cookies are created as temporary cookies which stored only in the browser’s memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:

Temporary cookies can not be used for tracking long-term information.

Persistent cookies can be used for tracking long-term information.

Temporary cookies are safer because no programs other than the browser can access them.

Persistent cookies are less secure because users can open cookie files see the cookie values.

What Is a Session?

A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.

There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.

Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

What’s PHP ?

The PHP Hypertext Preprocessor is a programming language that allows web developersto create dynamic content that interacts with databases. PHP is basically used for developing web based software applications.


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