Friday, June 27, 2014

PHP revisited

Q:1 What are the differences between Get and post methods in form submitting.
give the case where we can use get and we can use post methods?
A:1

When to use GET or POST

The HTML 2.0 specification says, in section Form
Submission (and the HTML 4.0 specification repeats this with minor
stylistic changes):
–>If the processing of a form is idempotent
(i.e. it has no lasting observable effect on the state of the
world), then the form method should be GET. Many database searches
have no visible side-effects and make ideal applications of query
forms.
–
–>If the service associated with the processing of a form has side
effects (for example, modification of a database or subscription to
a service), the method should be POST.

How the form data is transmitted?

quotation from the HTML 4.0 specification
–> If the method is “get” – -, the user agent
takes the value of action, appends a ? to it, then appends the form
data set, encoded using the application/x-www-form-urlencoded
content type. The user agent then traverses the link to this URI. In
this scenario, form data are restricted to ASCII codes.
–> If the method is “post” –, the user agent conducts an HTTP post
transaction using the value of the action attribute and a message
created according to the content type specified by the enctype
attribute.

Quote from CGI FAQ

Firstly, the the HTTP protocol specifies
differing usages for the two methods. GET requests should always be
idempotent on the server. This means that whereas one GET request
might (rarely) change some state on the Server, two or more
identical requests will have no further effect.
This is a theoretical point which is also good
advice in practice. If a user hits “reload” on his/her browser, an
identical request will be sent to the server, potentially resulting
in two identical database or
guestbook entries, counter increments, etc. Browsers may reload a
GET URL automatically, particularly if cacheing is disabled (as is
usually the case with CGI output), but will typically prompt the
user before
re-submitting a POST request. This means you’re far less likely to
get inadvertently-repeated entries from POST.
GET is (in theory) the preferred method for
idempotent operations, such as querying a database, though it
matters little if you’re using a form. There is a further practical
constraint that many systems have built-in limits to the length of a
GET request they can handle: when the total size of a request (URL+params)
approaches or exceeds 1Kb, you are well-advised to use POST in any
case.
I would prefer POST when I don’t want the status to
be change when user resubmits. And GET
when it does not matter.
   
Q:2 Who is the father of PHP and explain the changes in PHP versions?
A:2 Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current
generation of PHP, which uses the
Zend engine
under the
hood. PHP 5 uses
Zend engine 2 which,
among other things, offers many additionalOOP features
   
Q:3 How can we submit a form without a submit button?
A:3 The main idea behind this is to use Java script submit() function in
order to submit the form without explicitly clicking any submit button.
You can attach the document.formname.submit() method to onclick,
onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the
form after xx seconds once the loading is done (can be seen in online
test sites).
   
Q:4 In how many ways we can retrieve the data in the result set of
MySQL using PHP?
A:4 You can do it by 4 Ways1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc
   
Q:5 What is the difference between mysql_fetch_object and
mysql_fetch_array?
A:5 mysql_fetch_object() is similar tomysql_fetch_array(), with one difference -
an object is returned, instead of an array. Indirectly, that means that
you can only access the data by the field names, and not by their
offsets (numbers are illegal property names).
   
Q:6 What is the difference between $message and $$message?
A:6 It is a classic example of PHP’s variable variables. take the
following example.$message = “Mizan”;$$message = “is a moderator of PHPXperts.”;$message is a simple PHP variable that we are used to. But the
$$message is not a very familiar face. It creates a variable name $mizan
with the value “is a moderator of PHPXperts.” assigned. break it like
this${$message} => $mizanSometimes it is convenient to be able to have variable variable
names. That is, a variable name which can be set and used dynamically.
   
Q:7 How can we extract string ‘abc.com ‘ from a string ‘http://info@abc.com’
using regular expression of PHP?
A:7 preg_match(“/^http:\/\/.+@(.+)$/”,’http://info@abc.com’,$found);
echo $found[1];
   
Q:8 How can we create a database using PHP and MySQL?
A:8 We can create MySQL database with the use of
mysql_create_db(“Database Name”)
   
Q:9 What are the differences between require and include,
include_once and require_once?
A:9
The include() statement includes
and evaluates the specified file.The documentation below also applies to
require(). The two constructs
are identical in every way except how they handle
failure. include() produces a
Warning while require() results
in a Fatal Error. In other words, use
require() if you want a missing
file to halt processing of the page.
include() does not behave this way, the script will
continue regardless.
The include_once()
statement includes and evaluates the
specified file during the execution of
the script. This is a behavior similar
to the include()
statement, with the only difference
being that if the code from a file has
already been included, it will not be
included again. As the name suggests, it
will be included just once.include_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.
require_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.
   
Q:10 Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?
A:10 Yes we can use include() more than one time in any page though it is
not a very good practice.
   
Q: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)) ?
A:11 Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23 and as a result if
we do not specify the table name explicitly it will be assigned to the
default engine.
   
Q:12 Functions in IMAP, POP3 AND LDAP?
A:12 You can find these specific information in PHP Manual.
   
Q:13 How can I execute a PHP script using command line?
A:13 As of version 4.3.0, PHP supports a new SAPI type (Server
Application Programming Interface) named CLI which means Command Line
Interface. 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.
   
Q:14 Suppose your Zend engine supports the mode <? ?> Then how can u
configure your PHP Zend engine to support <?PHP ?> mode ?
A:14 In php.ini file:
set
short_open_tag=on
to make PHP support
   
Q:15 Shopping cart online validation i.e. how can we configure Paypal,
etc.?
A:15 We can find the detail documentation about different paypal
integration process at the following site


PayPal PHP
SDK : http://www.paypaldev.org
   
Q:16 What is meant by nl2br()?
A:16 Inserts HTML line breaks (<BR />) before all newlines in a string
string nl2br (string); Returns string with ” inserted before all
newlines. For example: echo nl2br(“god bless\n you”) will output “god
bless <br /> you” to your browser.
   
Q:17 Draw the architecture of Zend engine?
A:17 The Zend Engine is the internal compiler and runtime engine used by
PHP4. Developed by Zeev Suraski and Andi Gutmans, the Zend Engine is an
abbreviation of their names. In the early days of PHP4, it worked as
follows:
The PHP script was loaded by the Zend Engine and compiled into Zend
opcode. Opcodes, short for operation codes, are low level binary
instructions. Then the opcode was executed and the HTML generated sent
to the client. The opcode was flushed from memory after execution.Today, there are a multitude of products and techniques to help you
speed up this process. In the following diagram, we show the how modern
PHP scripts work; all the shaded boxes are optional.
PHP Scripts are loaded into memory and compiled into Zend opcodes.
   
Q:18 What are the current versions of apache, PHP, and MySQL?
A:18 As of February, 2007 the current versions arePHP: php5.2.1
MySQL: MySQL 5.2
Apache: Apache 2.2.4Note: visit www.php.net,
http://dev.mysql.com/downloads/mysql/,
www.apache.org to get current
versions.
   
Q:19 What are the reasons for selecting lamp (Linux, apache, MySQL,
PHP) instead of combination of other software programs, servers and
operating systems?
A:19 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.
   
Q:20 How can we encrypt and decrypt a data present in a MySQL table
using MySQL?
A:20 AES_ENCRYPT () and AES_DECRYPT ()
   
Q:21 How can we encrypt the username and password using PHP?
A:21 The functions in this section perform encryption and decryption, and
compression and uncompression:
encryption decryption
AES_ENCRYT() AES_DECRYPT()
ENCODE() DECODE()
DES_ENCRYPT() DES_DECRYPT()
ENCRYPT() Not available
MD5() Not available
OLD_PASSWORD() Not available
PASSWORD() Not available
SHA() or SHA1() Not available
Not available UNCOMPRESSED_LENGTH()
   
Q:22 What are the features and advantages of object-oriented
programming?
A:22 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
   
Q:23 What are the differences between procedure-oriented languages and
object-oriented languages?
A:23 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.
   
Q:24 What is the use of friend function?
A:24 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
which names 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.
   
Q:25 What are the differences between public, private, protected,
static, transient, final and volatile?
A:25 Public: Public declared items can be accessed everywhere.
Protected: Protected limits access to inherited and parent
classes (and to the class that defines the item).
Private: Private limits visibility only to the class that defines
the item.
Static: A static variable exists only in a local function scope,
but it does not lose its value when program execution leaves this scope.
Final: Final keyword prevents child classes from overriding a
method by prefixing the definition with final. If the class itself is
being defined final then it cannot be extended.
transient: A transient variable is a variable that may not
be serialized.
volatile: a variable that might be concurrently modified by multiple
threads should be declared volatile. Variables declared to be volatile
will not be optimized by the compiler because their value can change at
any time.
   
Q:26 What are the different types of errors in PHP?
A:26 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 behavior.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 behavior is to display them to the user
when they take place.
   
Q:27 What is the functionality of the function strstr and stristr?
A:27 strstr:
Returns part of haystack
string from the first occurrence of
needle to the end of
haystack.If needle is not found,
returns FALSE.
If needle is not a
string, it is converted to an integer and applied as the
ordinal value of a character.
This function is case-sensitive. For
case-insensitive searches, use
stristr().
   
Q:28 What are the differences between PHP 3 and PHP 4 and PHP 5?
A:28 Please read the release notes at
http://www.php.net.
   
Q:29 How can we convert asp pages to PHP pages?
A:29 there are lots of tools available for asp to PHP conversion. you can
search Google for that. the best one is available athttp://asp2php.naken.cc./
   
Q:30 What is the functionality of the function htmlentities?
A:30 Convert all applicable characters to HTML entities
This function is identical to htmlspecialchars() in all ways, except
with htmlentities(), all characters which have HTML character entity
equivalents are translated into these entities.
   
Q:31 How can we get second of the current time using date function?
A:31 $second = date(“s”);
   
Q:32 How can we convert the time zones using PHP?
A:32 By using date_default_timezone_get and
date_default_timezone_set function on PHP 5.1.0 
<?php
// Discover what 8am in Tokyo relates to on the East Coast of the US    

// Set the default timezone to Tokyo time:
date_default_timezone_set('Asia/Tokyo');    

// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);    

// Now set the timezone back to US/Eastern
date_default_timezone_set('US/Eastern');    

// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo '<p>', date(DATE_RFC1123, $stamp) ,'</p>';?>
   
Q:33 What is meant by urlencode and urldocode?
A:33 URLencode returns a string in which all non-alphanumeric characters
except -_. have been replaced with a percent (%)
sign followed by two hex digits and spaces encoded as plus (+)
signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in
application/x-www-form-urlencoded media type.
urldecode decodes any %##
encoding in the given string.
   
Q:34 What is the difference between the functions unlink and unset?
A:34 unlink() deletes the given file from the file system.
unset() makes a variable undefined.
   
Q:35 How can we register the variables into a session?
A:35 $_SESSION[’name’] = “Mizan”;
   
Q:36 How can we get the properties (size, type, width, height) of an
image using PHP image functions?
A:36 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 t
   
Q:37 How can we get the browser properties using PHP?
A:37 By using
$_SERVER['HTTP_USER_AGENT']
variable.
   
Q:38 What is the maximum size of a file that can be uploaded using PHP
and how can we change this?
A:38 By default the maximum size is 2MB. and we can change the following
setup at php.iniupload_max_filesize = 2M
   
Q:39 How can we increase the execution time of a PHP script?
A:39 by changing the following setup at php.inimax_execution_time = 30
; Maximum execution time of each script, in seconds
   
Q:40 How can we take a backup of a MySQL table and how can we restore
it. ?
A:40 To backup: BACKUP TABLE tbl_name[,tbl_name…] TO
‘/path/to/backup/directory’
RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or
for transferring the data to another SQL server (not necessarily a MySQL
server). The dump will contain SQL statements to create the table and/or
populate the table.
-t, –no-create-info
Don’t write table creation information (the CREATE TABLE statement).
-d, –no-data
Don’t write any row information for the table. This is very useful if
you just want to get a dump of the structure for a table!
   
Q:41 How can we optimize or increase the speed of a MySQL select
query?
A:41
  • first of all instead of using select * from table1, use select
    column1, column2, column3.. from table1
  • Look for the opportunity to introduce index in the table you are
    querying.
  • use limit keyword if you are looking for any specific number of
    rows from the result set.
   
Q:42 How many ways can we get the value of current session id?
A:42 session_id() returns the session id for the current session.
   
Q:43 How can we destroy the session, how can we unset the variable of
a session?
A:43 session_unregister — Unregister a global variable from the current
session
session_unset — Free all session variables
   
Q:44 How can we destroy the cookie?
A:44 Set the cookie in past.
   
Q:45 How many ways we can pass the variable through the navigation
between the pages?
A:45
  • GET/QueryString
  • POST
   
Q:46 What is the difference between ereg_replace() and eregi_replace()?
A:46 eregi_replace() function is identical to ereg_replace() except that
this ignores case distinction when matching alphabetic
characters.eregi_replace() function is identical to ereg_replace()
except that this ignores case distinction when matching alphabetic
characters.
   
Q:47 What are the different functions in sorting an array?
A:47 Sort(), arsort(),
asort(), ksort(),
natsort(), natcasesort(),
rsort(), usort(),
array_multisort(), and
uksort().
   
Q:48 How can we know the count/number of elements of an array?
A:48 2 ways
a) sizeof($urarray) This function is an alias of count()
b) count($urarray)
   
Q:49 What is the PHP predefined variable that tells the What types of
images that PHP supports?
A:49 Though i am not sure if this is wrong or not, With the exif
extension you are able to work with image meta data.
   
Q:50 How can I know that a variable is a number or not using a
JavaScript?
A:50 bool is_numeric ( mixed var)
Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.
   
Q:51 List out some tools through which we can draw E-R diagrams for
mysql.
A:51 Case Studio
Smart Draw
   
Q:52 How can I retrieve values from one database server and store them
in other database server using PHP?
A:52 we can always fetch from one database and rewrite to another. here
is a nice solution of it.$db1 = mysql_connect(“host”,”user”,”pwd”)
mysql_select_db(“db1″, $db1);
$res1 = mysql_query(“query”,$db1);$db2 = mysql_connect(“host”,”user”,”pwd”)
mysql_select_db(“db2″, $db2);
$res2 = mysql_query(“query”,$db2);At this point you can only fetch records from you previous ResultSet,
i.e $res1 – But you cannot execute new query in $db1, even if you
supply the link as because the link was overwritten by the new db.so at this point the following script will fail
$res3 = mysql_query(“query”,$db1); //this will failSo how to solve that? take a look below.
$db1 = mysql_connect(“host”,”user”,”pwd”)
mysql_select_db(“db1″, $db1);
$res1 = mysql_query(“query”,$db1);
$db2 = mysql_connect(“host”,”user”,”pwd”, true)
mysql_select_db(“db2″, $db2);
$res2 = mysql_query(“query”,$db2);
So mysql_connect has another optional boolean parameter which
indicates whether a link will be created or not. as we connect to the
$db2 with this optional parameter set to ‘true’, so both link will
remain live.
now the following query will execute successfully.
$res3 = mysql_query(“query”,$db1);
Thanks goes to Hasan and Hasin for this solution.
   
Q:53 List out the predefined classes in PHP?
A:53 Directory
stdClass
__PHP_Incomplete_Class
exception
php_user_filter
   
Q:54 How can I make a script that can be bi-language (supports
English, German)?
A:54 You can maintain two separate language file for each of the
language. all the labels are putted in both language files as variables
and assign those variables in the PHP source. on runtime choose the
required language option.
   
Q:55 What are the difference between abstract class and interface?
A:55 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.
   
Q:56 How can we send mail using JavaScript?
A:56 JavaScript does not have any networking capabilities as it is
designed to work on client site. As a result we can not send mails using
JavaScript. But we can call the client side mail protocol mailto
via JavaScript to prompt for an email to send. this requires the client
to approve it.
   
Q:57 How can we repair a MySQL table?
A:57 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
   
Q:58 What are the advantages of stored procedures, triggers, indexes?
A:58 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.
   
Q:59 What is the maximum length of a table name, database name, and
fieldname in MySQL?
A:59 The following table describes the maximum length for each type of
identifier.
Identifier Maximum Length
(bytes)
Database 64
Table 64
Column 64
Index 64
Alias 255
There are some restrictions on the characters that may appear in
identifiers:
   
Q:60 How many values can the SET function of MySQL take?
A:60 MySQL set can take zero or more values but at the maximum it can
take 64 values
   
Q:61 What are the other commands to know the structure of table using
MySQL commands except explain command?
A:61 describe Table-Name;
   
Q:62 How many tables will create when we create table, what are they?
A:62 The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,
   
Q:63 What is the purpose of the following files having extensions 1) .frm
2) .myd 3) .myi? What do these files contain?
A:63 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,
   
Q:64 What is maximum size of a database in MySQL?
A:64 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 LimitLinux 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
   
Q:65 Give the syntax of Grant and Revoke commands?
A:65 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 privileges
b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* 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 userThe generic syntax for revoke is as following
> REVOKE [rights] on [database/s] FROM [username@hostname]
now rights can be as explained above
a) All privileges
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
   
Q:66 Explain Normalization concept?
A:66 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 FormThe 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 FormWhere 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
   
Q:67 How can we find the number of rows in a table using MySQL?
A:67 Use this for mysql
>SELECT COUNT(*) FROM table_name;
   
Q:68 How can we find the number of rows in a result set using PHP?
A:68 $result = mysql_query($sql, $db_link);
$num_rows = mysql_num_rows($result);
echo "$num_rows rows found";
   
Q:69 How many ways we can we find the current date using MySQL?
A:69 SELECT CURDATE();
CURRENT_DATE() = CURDATE()
for time use
SELECT CURTIME();
CURRENT_TIME() = CURTIME()
   
Q:70 What are the advantages and disadvantages of Cascading Style
Sheets?
A:70 External Style SheetsAdvantagesCan 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
contextsDisadvantagesAn 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 definitionsEmbedded 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
   
Q:71 What type of inheritance that PHP supports?
A:71 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’.
   
Q:72 What is the difference between Primary Key and
Unique key?
A:72 Primary Key: A column in a table whose values uniquely identify the
rows in the table. A primary key value cannot be NULL. Unique Key: Unique Keys are used to uniquely identify each row in the
table. There can be one and only one row for each unique key value. So
NULL can be a unique key.There can be only one primary key for a table but there can be more
than one unique for a table.
   

Q:73		 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 999 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 999) and
insert another row then. What is the value for this auto incremented
field user_pri_id
A:73 In both cases let the value for auto increment field be n then next
row will have value n+1 i.e. 1000
   
Q:74 What are the advantages/disadvantages of MySQL and PHP?
A:74 Both of them are open source software (so free of cost), support
cross platform. php is faster then ASP and JSP.
   
Q:75 What is the difference between GROUP BY and ORDER BY in Sql?
A:75 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
   
Q:76 What is the difference between char and varchar data types?
A:76 Set char to occupy n bytes and it will take n bytes even if u r
storing a value of n-m bytes
Set varchar to occupy n bytes and it will take only the required space
and will not use the n bytes
eg. name char(15) will waste 10 bytes if we store ‘mizan’, if each char
takes a byte
eg. name varchar(15) will just use 5 bytes if we store ‘mizan’, if each
char takes a byte. rest 10 bytes will be free.
   
Q:77 What is the functionality of md5 function in PHP?
A:77 Calculate the md5 hash of a string. The hash is a 32-character
hexadecimal number. I use it to generate keys which I use to identify
users etc. If I add random no techniques to it the md5 generated now
will be totally different for the same string I am using.
   
Q:78 How can I load data from a text file into a table?
A:78 you can use LOAD DATA INFILE file_name; syntax to load data
from a text file. but you have to make sure thata) data is delimited
b) columns and data matched correctly
   
Q:79 How can we know the number of days between two given dates using
MySQL?
A:79 SELECT DATEDIFF(’2007-03-07′,’2005-01-01′);
   
Q:80 How can we know the number of days between two given dates using
PHP?
A:80 $date1 = date(‘Y-m-d’);
$date2 = ’2006-08-15′;
$days = (strtotime($date1) – strtotime($date2)) / (60 * 60 * 24);
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PHP extra

Which is the latest version of PHP ?
The latest stable version of PHP is 5.5.14 released at 27 June 2014 .
What is PHP.
PHP is an open source server side scripting language used to develop dynamic websites . PHP  stands for Hypertext Preprocessor , also stood for  Personal Home Page . Now the implementations of PHP is produced by The PHP group .It was created by Rasmus lerdorf in 1995 . It is a free software released under the PHP license .

Who is the father of PHP ?
Rasmus Lerdorf known as the father of PHP . Php was created by Rasmus Lerdorf In 1995 .

What is the current version of Apache ?
The latest  stable version of  Apache  is  2.4.9, released  on 17th  March 2014.
What is difference between unset and unlink..
Unset is used to delete(destroy) a variable whereas unlink used to delete a file.
Which is the latest version of PHP.
The latest stable version of PHP is 5.4.11 released at 17 January 2013 .
What is the difference between array_merge and array_combine.
array_merge merges the elements of one or more than one array such that the value of one array appended at the end of first array. If the arrays have same strings  key  then the later value overrides the previous value for that key .

<?php
$array1 = array("course1" => "java","course2" => "sql");
$array2 = array(("course1" => "php","course3" => "html");
$result = array_merge($array1, $array2);
print_r($result);
?>
OUTPUT : 
array
(
[course1] => php
[course2] => sql
[course3] => html
)

Array_combine creates a new array by using the key of one array as keys and using the value of other array as values.
<?php
$array1    = array("course1","course2");
$array2    = array(("php","html");
$new_array = array_combine($array1, $array2);
print_r($new_array);
?>
OUTPUT :
array
(
[course1]  => php
[course2]    => html
)
What is the difference between session and cookies.
There are some difference between session and cookies thath are as following:-

1 : Session are temporary and Cookies are parmanent.

2 : Session data is store on server while Cookies are store on user's computer.

3 :Cookies contents can be easily modify but to modify Session contents is very hard.

4 :Cookies could be save for future reference but Session couldn't when user close the browser Session data also lost.
How we declare cookies and how we expire it.
setcookie() function is used to set cookies in php.
To declare Cookies syntax will be:-    setcookie(name, value, expire, path, domain);
name    : Name of the cookie
value     : Value of the cookie
expire   : The time for cookie to expire
path      : path to save the cookie where we want to save the cookie information
domain : domain name on which we want to save the cookie
     
e.g    :  setcookie("username","harry",time()+60*60*60*24);
In the above example the cookie name is username having value harry and set for one day .
To expire cookies we have set the time of cookie in past
To expire Cookies syntax will be:     setcookie(name,value,time-3600);
What is use of var_dump .
var_dump() function is used to display structured information(type and value) about one or more variable.
syntax:- var_dump(variable1,variable2,.....variablen);
e.g    <?php
          $a=3.1;
          $b=true;
          var_dump($a,$b);
         ?>
output   :  float(3.1)
              bool(true)
What is str_replace().
This function replace some characters with some other characters in a string , this function is case sensitive.
syntax:- str_replace(find,replace,string);

find:-required,specifies the value to find.
replace:-required,specifies the value to replace the value in find.
string:-required,specifies the string to searched.

for examlpe:-
<?php
echo str_replace("world","india","hello world");
?>
output:-     hello india
What is the difference between include() and require().
include() function gives the warning when specified file not found but all script will be continually  executed.
e.g.    <?php
                  include("filename.php");
                  echo "hello";
              ?>
output:- hello
In the above  example if file not found then it gives warning and print the hello because warning does not  stop script and echo will be execute.
require() function gives the fatal error when specifies file is not found and stop the script. 
e.g.    <?php

                require("filename.php");
                echo "hello";
           ?>
output:-   it gives fatal error and stop the script ,echo will not be executed.
What is final class.
final class is a class that can not be inherited.Its protect the methods of class to be overriden by the child classes.
e.g.    final class baseclass
            {
                public function mymethod()  {
                          echo  "baseclass method";
                            }

            }

            class derivedclass extends baseclass
             {
                        public function mymethod() {
                                 echo   "derivedclass method";

                              }

               }

          $c= new derivedclass();
          $c->mymethod();

  In the above example base class is declared as final and hence can not be inherited.
 derived class tries to extends baseclass then compile error will be generated.
What is difference between abstract class and interface classes.
Interface : An interface does not contain any code,it contain only declaration of    methods,properties,events. Interfaces allow us to code which specifies which methods a class must have implement . Interfaces defines with the word interface . All methods in interfaces must be public
           e.g :     interface myItem

                    {

                        void Id();
                       string description();
                        string Runtest(int testnumber);

                    }

 Abstract class : Abstract classes are look like interfaces.Abstract classes may contain code although it may also have abstract method that do not have code. Abstract classes defines only signature of the method ,not implementation.  The child class which inherit the abstarct class must define all the abstarct methods of its parent class .

         e.g        abstract class myItem

                    {

                        abstract protected function getitem();
                        abstract protected function setitem();

                    }
What is difference between echo() and print().
echo() and print() function both are used to show the output on the visitors screen but in echo we can take  one or more parameters.

 print() has a return value of true or false whereas echo has a void return type.

 echo() is slightly faster than print.
What is the difference between PHP4 and PHP5.
There are some difference between PHP4 and PHP5 that are as following:-

      1) In PHP5 abstract classes are used but not used in PHP4.

      2) In PHP5 interfaces are used but not used in PHP4.

      3) In PHP5 visibility are used but not used in PHP4.

      4) In PHP5 magic methods are used but not uesd in PHP4.

      5) In PHP5 typehinting are used but not used in PHP4.

      6) In PHP5 cloning are used but not used in PHP4.

      7) In PHP5 construtor are written as __construct keyword but in PHP4 are written as class name.
How many types of errors in PHP.
There are mainly three types of error in php. These are -

       (1) Notice error

       (2) Warning error

       (3) Fatal error

 Notice error happened when a variable not decleared but it is used.

Warning error occurred when a package not defined and some functionality has been used in the program.These are not serious errors,       they continue the execution of script.

 And Fatal error are those errors when an object call a class and the class not present there.These errors are serious     error  which can stop the execution of script
Why do we use ob_start().
Ob_start used to active the output buffering .When output buffering is on all output of the page sent at one time to the browser ,otherwise sometimes we face headers already sent type errors.
What is a .htacces file.
.htaccess is a configuration file running on Apache server.These .htaccess file used to change the functionality and features of apache web  server .

 e.g   .htaccess file used for url rewrite .

           .htaccess file used to make the site password protected.

           .htaccess file can restrict  some ip addresses ,so that on restricted ip adresses  site will not open.
Is PHP an interpreted language or compiler language.
PHP is an interpreted language.
What is the difference between compiler language and interpreted language.
 Interpreted language executes line by line  , if there is some error on a line it stops the execution of script.

Compiler language can execute the whole script at a time and gives all the errors at a time. It does not stops the execution of script ,if there is some error on some line.

What are web services in PHP.
Web services converts our applicaton into a web-application ,which can publish its functions and messages to the internet users.The main web services platform is XML and HTTP.Web services can be published ,found and used through web.
What is static methods and properties in PHP.
A static method is accessible without needing instantiation of  a class. It means there is no need to make an  object to call the static methods .Static  methods and properties can be directly call from its class name with (::)  a scope resolution operator. They cannot be call from the object of its class. We need static methods to overcome   long overhead of instantiation of classes .
  e.g
  <?php

      Class foo
      {
        public static  $variable_name = 'it is a static variable';
      }
      echo foo :: $variable_name;      // Output  :  it is a static varaible  

  ?>
What are magic methods in PHP..
Magic methods are very easy to identify, that every magical method name is started with double underscore( __)sign. We can not declare any user-defined functions with __ sign.

Some magic methods are :

__construct() , __destruct()  ,    __call()   ,  __callStatic()  ,  __get(),  __set()     , __isset()     ,__unset()
,  __sleep()       ,  __wakeup(),   __toString()  , __invoke()    , __set_state() ,  __clone().
What is the difference between GET and POST methods.
 GET Method:

  1) All the name value pairs are submitted as a query string in URL.

  2) It's not secured.

  3) Length of the string is restricted about 256.

  4) If method is not mentioned in the Form tag, this is the default method used.

  5) Data is always submitted in the form of text.


 POST Method:

  1) All the name value pairs are submitted in the Message Body of the request.

  2) Length of the string (amount of data submitted) is not restricted.

  3) Post Method is secured because Name-Value pairs cannot be seen in location bar of the web browser.

  4) If post method is used and if the page is refreshed it would prompt before the request is resubmitted.

  5) If the service associated with the processing of a form has side effects (for example, modification of a
       database or subscription to a service), the method should be POST.

What are access control modifiers in php.
Keywords public,protected and private are the three types of access control modifiers in php.With  the help of these  keywords we can manage  the accessing  of a method or property of a class  in php
What is difference between public, private and protected in php.
Public :    
The items which are declared public can be access from everywhere ie access from inside the class ,access in inherited class and   access from outside the class.

Protected :
The items which are declared protected can be access inside the class that defines the item  and can acess in its child classes  (ie access in its inherited class) .

Private :
The items which are declared private can only be access inside its class that defines the item.
How can we get all the properties of browser in PHP.
We can get the browser properties in PHP by :
<?php
$_SERVER ['HTTP_USER_AGENT'] ;
?>
How to get difference between two dates.
$firstdate               = "2010-10-07";
$seconddate        = "2014-03-10";

$differnce              = abs(strtotime($date2) - strtotime($date1));

$years                   =   floor($differnce / (365*60*60*24));
$months               =   floor(($differnce - $years * 365*60*60*24) / (30*60*60*24));
$days                    =   floor(($differnce- $years * 365*60*60*24 - $months*30*60*60*24)/ (60*60*24));

printf("%d years, %d months, %d daysn", $years, $months, $days);
How to get the names of all included and required files for a particular page in PHP.
The function get_included_files ()  function is used to get  the names of all  required and included files in a page  . It returns an array with the names of included and required files in a page
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PHP for freshers

1.Question : Who is the father of PHP and explain the changes in PHP versions?
Answer : Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3 is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current generation of PHP, which uses the Zend engine under the hood. PHP 5 uses Zend engine 2 which, among other things, offers many additional OOPs features.
2.Question : How can we submit a form without a submit button?
Answer : The main idea behind this is to use Java script submit() function in order to submit the form without explicitly clicking any submit button. You can attach the document.formname.submit() method to onclick, onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the form after xx seconds once the loading is done (can be seen in online test sites).
3.Question : In how many ways we can retrieve the data in the result set of
MySQL using PHP?
Answer : You can do it by 4 Ways
1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc
4.Question : How can we extract string ‘hotmail.com ‘ from a string raghav.cool@hotmail.com using regular expression of PHP?
Answer : preg_match(”/^http://invalid.invalid/@(.+)$/”,’raghav.cool@hotmail.com’,$found);
echo $found[1];
5.Question : How can we create a database using PHP and MySQL?
Answer : We can create MySQL Database with the use of mysql_create_db(“Database Name”).
6.Question : Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?
Answer : Yes we can use include() more than one time in any page though it is not a very good practice.
7.Question : What is meant by urlencode and urldecode?
Answer : URLencode returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in application/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string.
8.Question : 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.
9.Question : What is meant by urlencode and urldecode?
Answer : URLencode returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in application/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string.
10.Question : 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.
11.Question : How can we register the variables into a session?
Answer : $_SESSION[’name’] = “RAGHAV”;
12.Question : How can we get the browser properties using PHP?
Answer : By using
$_SERVER[’HTTP_USER_AGENT’] variable.
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