Learn PHP Lacture2

Overview of My SQL Structure and
Syntax
Databases are stores of information.
MySQL is an open-source database that can be used for web
applications.
The only requirement is that, you need to have a server at your
disposal where you can install MySQL.
Types of Storage Engines
◦ MyISAM (Indexed Sequential Access Method)
◦ MERGE
◦ MEMORY
◦ InnoDB
◦ BDB (BerkeleyDB )

My SQL Syntax and
Commands
Common commands
◦ CREATE : Creates new databases and tables
◦ ALTER : Modifies existing tables
◦ SELECT : Chooses the data you want
◦ DELETE : Erases the data from your table
◦ DESCRIBE : Lets you know the structure and
specifics of the table
◦ INSERT INTO table name VALUES : Puts values
into the table
◦ UPDATE : Lets you modify data already in a table
◦ DROP : Deletes an entire table or database

Data Type in
MySQL Text Types
◦ char(size)
It is used to store no. of character and it is in fixed length.
◦ varchar(size)
It is used to store alphanumeric data of variable length.
◦ blob
It is binary large object which can hold variable amount of business data
◦ Binary and Varbinary
These 2 type are similar to char and varchar except that they hold
binary string rather than ascii string
 Number Types
◦ int(size)
It is used to store integer type of data.
It divide in to 5 segment int, tiny int, small int, medium int,big int
◦ Float(size,precision)
It is allow to store decimal numbers with specific precision.
◦ Double(size,precision)
It is allow to store large floating decmial point value.

Date
◦ Hold the date value
◦ Range between 1000-01-01 to 9999-12-31
Time
◦ Hold the time value
◦ Standard format hh:mm:ss
Datetime
◦ It hold date and time value
◦ Range between 1000-01-01 00:00:00 to 9999-12-31 23:59:59
◦ Standard format yyyy-mm-dd hh:mm:ss
year
◦ It is required 1 byte for holds year value

How PHP Fits with My
SQLYou can use MySQL commands within PHP code.
Some of the more commonly used functions are:
◦ mysql_connect($host, $username, $password) : Connects to the
MySQL server and returns a resource which is used to reference the
connection.
◦ Mysql_pconnect():-
◦ mysql_select_db($database, $resource) : Equivalent to the MySQL
command USE and sets the active database.
◦ mysql_query($query, $resource) : Used to send any MySQL
command to the database server. In the case of SELECT queries, a
reference to the result set will be returned.
◦ mysql_fetch_array($result) : Return a row of data from the query ’
s result set as an associative array, numeric array or both.
◦ mysql_fetch_assoc($result) : Return a row of data from the query ’
s result set as an associative array.
◦ mysql_error([$resource]) : Shows the error message generated by
the previous query.
◦ die(<String> $msg)
die() prints message and exits the current script.

Cont…
To connect with database
◦ $con = mysql_connect ($host, $username, $password)
$host = ‘localhost’;
$user = ‘root’;
$pass = ‘’;
$con = mysql_connect($host, $user, $pass);
The following statement has the same effect:
$con = mysql_connect(‘localhost’, ‘root’, ‘’);
To close the connection
◦ mysql_close($con);
To select database
$db = mysql_select_db(DBName,$con)

Create
Table
Syntax:-
◦ CREATE TABLE table_name
(
column_name1 data_type,
....
)
Example:-
◦ CREATE TABLE Persons
(
FirstName varchar(15),
LastName varchar(15),
Age int
)
Important: A database must be selected before a table can be
created. The database is selected with the mysql_select_db()
function.

Insert data into tables
The INSERT INTO statement is used to add new records to a database table.
It is possible to write the INSERT INTO statement in two forms.
The first form doesn't specify the column names where the data will be
inserted, only their values:
INSERT INTO table_name VALUES (value1, value2, value3,...)
The second form specifies both the column names and the values to be
inserted:
INSERT INTO table_name (column1, column2, column3,...) VALUES (value1,
value2, value3,...)
To get PHP to execute the statements above we must use the mysql_query()
function. This function is used to send a query or command to a MySQL
connection.
Example:-
// insert data into table
$insert=mysql_query("INSERT INTO Persons VALUES (1, 'Glenn',
'Quagmire',33 )");
// Execute query
mysql_query($insert,$con);
// insert data into table
$insert=mysql_query("INSERT INTO Persons (personID,FirstName,
LastName, Age) VALUES (2,'Peter', 'Griffin',35)");

Insert data into table using
FORM<html>
<body>
<form action="insert.php" method="post">
Firstname: <input type="text"
name="firstname">
Lastname: <input type="text"
name="lastname">
Age: <input type="text" name="age">
<input type="submit">
</form>
</body>
</html>
When a user clicks the submit button in the HTML
form in the example above, the form data is sent to
"insert.php".

Here is the "insert.php" page:
<?php
$con = mysql_connect('localhost', 'root', '') or
die ('Unable to connect. Check your connection
parameters.');
echo "Connection successfullyn";
// select database
mysql_select_db('student', $con) or die(mysql_error($con));
echo "Database activen";
//insert data
$sql="INSERT INTO Persons (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";
if (!mysql_query($sql,$con))
{
die('Error: ' . mysql_error());
}
echo "1 record added";
mysql_close($con);
?>

Retrieve the Data From a Database
Table$result = mysql_query("select * from Persons ")
To retrive the data from the table we are using the
mysql_fetch_array() function.
When we pass $result into the mysql_fetch_array function --
mysql_fetch_array($result) -- an associative array (firstname,
lastname, age) is returned.
mysql_fetch_array() function to return the first row from the
recordset as an array.
In our MySQL table " Persons," there are only three fields that we
care about: firstname, lastname and age.
These names are the keys to extracting the data from our
associative array.
To get the firstname we use $row[‘firstname'] , to get the
lastname we use $row[‘lastnamr'] and to get the age we
use $row['age'].

fetch array while
loopEach call to mysql_fetch_array() returns the next row
in the recordset.
$result = mysql_query("SELECT * FROM Persons");
while($row = mysql_fetch_array($result))
{
echo $row['FirstName'] . " " .
$row['LastName'].””.$row[‘age’];
echo "<br />";
}
The while loop loops through all the records in the
recordset.
To print the value of each row, we use the PHP $row
variable ($row['FirstName']
,$row['LastName'],$row[‘age’]).

Retrieving data
To retrieving the data from database 2 function are used.
◦ mysql_fetch_array()
◦ mysql_fetch_assoc()
The mysql_fetch_assoc() function returns a single row from the table
as an associative array. The data can be retrieved by using the column
names as indexes.
The mysql_fetch_array() function returns a single row from the table.
The data can be retrieved by column names and column indexes.
@ is used to generate user defined exception other than System
generated errors.
mysql_num_fields( $result ) is used to count total number of fields and
coloumn from your database.
$num_cols = mysql_num_fields( $result );
mysql_num_rows( $result ) is used to count total number of recods
from your database.
$num_rows = mysql_num_rows( $result );

Include() AND include_once()
Include() AND require():-
◦ The include and require statements are used to insert useful
codes written in other files, in the flow of execution.
◦ Include and require are identical, except upon failure:
require will produce a fatal error (E_COMPILE_ERROR) and stop the script
include will only produce a warning (E_WARNING) and the script will
continue
So, if you want the execution to go on and show users the output, even if
the include file is missing, use include(). Otherwise, require().
◦ Syntax:-
Include(“file name with path”); or include “file name with path”;
Require(“file name with path”); or require “file name with path”;
◦ Example:-
<html>
<body>
<?php include 'header.php'; ?>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
</body>
</html>

Include_once() AND
require_once()
Include_once() & require_once() both are functioning same as
include() and require.
But the main difference between those function is include_once()
and require_once() include file only once while include() and
require() include files as many time as you want.
◦ Syntax:-
Include_once(“file name with path”); or include_once “file name with path”;
Require_once(“file name with path”); or require_once “file name with path”;
◦ Example:-
<html>
<body>
<?php include_once 'header.php'; ?>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
</body>
</html>

Maintaining State in PHP using Cookies &
Sessions
Why to maintain state in php?
◦ HTTP is stateless Protocol.
◦ Any data you have stored is forgotten about
when the page has been sent to the client
and the connection is closed.
◦ Cookie is tiny bits of information that a web
site could store on the client's machine that
were sent back to the web site each time a
new page was requested. Each cookie could
only be read by the web site that had written
it.

What is a Cookie?
A cookie is a small text file that is
stored on a user’s computer.
Each cookie on the user’s computer is
connected to a particular domain.
Each cookie be used to store up to
4kB of data.
A maximum of 20 cookies can be
stored on a user’s PC per domain.

1. User sends a request for page at
www.example.com for the first time.
Exampl
e
page request

2. Server sends back the page xhtml to
the browser AND stores some data in
a cookie on the user’s PC.
Exampl
e
cookie data
xhtml

3. At the next page request for domain
www.example.com, all cookie data
associated with this domain is sent
too.
Exampl
e
page request
cookie data

setcookie(name [,value [,expire [,path [,domain
[,secure]]]]])
name = cookie name
value = data to store (string)
expire = UNIX timestamp when the cookie expires.
Default is that cookie expires when browser is closed.
path = Path on the server within and below which the
cookie is available on.
domain = Domain at which the cookie is available for.
secure = If cookie should be sent over HTTPS
connection only. Default false.
Set a
cookie

setcookie(‘name’,’Robert’)
This command will set the cookie called name on
the user’s PC containing the data Robert. It will be
available to all pages in the same directory or
subdirectory of the page that set it (the default path
and domain). It will expire and be deleted when the
browser is closed (default expire).
setcookie(‘age’,’20’,time()+60*60*24*30)
This command will set the cookie called age on
the user’s PC containing the data 20. It will be available
to all pages in the same directory or subdirectory of the
page that set it (the default path and domain). It will
expire and be deleted after 30 days.
Set a cookie -
examples

As the setcookie command involves
sending a HTTP header request, it must
be executed before any xhtml is
echoed to the browser, including
whitespace.
Where to write code for Cookie…
correct!
incorrect.
echoed
whitespace
before
setcookie

All cookie data is available through the
superglobal $_COOKIE:
$variable = $_COOKIE[‘cookie_name’]
or
$variable = $HTTP_COOKIE_VARS[‘cookie_name’];
e.g.
$age = $_COOKIE[‘age’]
Read cookie
data

To remove a cookie, simply overwrite the
cookie with a new one with an expiry time
in the past…
setcookie(‘cookie_name’,’’,time()-
6000)
Delete a
cookie

You can store user information (e.g. username,
items selected, etc.) in the server side for later
use using PHP session.
Sessions work by creating a unique id (UID) for
each visitor and storing variables based on this
UID.
The UID is either stored in a cookie or is
propagated in the URL.
PHP
Sessions
<?php session_start(); ?>
<html>
<body>
</body>
</html>
session_start() function must appear BEFORE the <html>
tag.
Before you can store user information in your PHP
session, you must first start up the session.

PHP
Sessions Starting a PHP session:
<?php
session_start();
?>
• This tells PHP that a session is requested.
• A session ID is then allocated at the server
end.
• session ID looks like:
sess_f1234781237468123768asjkhfa78912
34g

 $_SESSION
 e.g., $_SESSION[“intVar”] = 10;
 Testing if a session variable has been
set:
session_start();
if(!$_SESSION['intVar']) {...} //intVar is set or not
Session
variables

Session
Example 1<?php
session_start();
if (!isset($_SESSION["intVar"]) ){
$_SESSION["intVar"] = 1;
} else {
$_SESSION["intVar"]++;
}
echo "<p>In this session you have accessed this
page " . $_SESSION["intVar"] . "times.</p>";
?>

Ending
sessionsunset($_SESSION[‘name’])
–Remove a session variable
session_destroy()
– Destroys all data registered to a session
– does not unset session global variables and cookies
associated with the session
–Not normally done - leave to timeout

Learn PHP Lacture2

Recommended

Recommended

More Related Content

What's hot

What's hot (18)

Similar to Learn PHP Lacture2

Similar to Learn PHP Lacture2 (20)

Recently uploaded

Recently uploaded (20)

Learn PHP Lacture2