This document discusses MySQLi functions in PHP for interacting with MySQL databases. It covers connecting to a database, selecting a database, creating and dropping databases and tables, and executing queries. Functions covered include mysqli_connect(), mysqli_query(), and mysqli_fetch_assoc(). Examples are provided for common tasks like connecting, selecting a database, and creating/deleting tables.

1. CN5109
WEB APPLICATION
DEVELOPMENT
Chapter 7
MySQLi – Working with Database and Table

2. MySQLi PHP Syntax
• MySQLi works very well in combination of various
programming languages like PERL, C, C++, JAVA and PHP.
• Out of these languages, PHP is the most popular one because
of its web application development capabilities.
• The PHP functions for use with MySQLi have the following
general format:
mysqli_function(value,value,...);

3. MySQLi PHP Syntax
• Example:
<?php
$variable = mysqli_function(value, [value,...]);
if( !$variable )
{
Some codes … ;
}
// Otherwise MySQLi or PHP Statements
?>

4. MySQLi Functions
Function Description
mysqli_connect() Opens a new connection to the MySQL server
mysqli_error()
Returns the last error description for the most recent
function call
mysqli_query() Performs a query against the database
mysqli_fetch_assoc() Fetches a result row as an associative array
mysqli_close() Closes a previously opened database connection

5. MySQLi Connection
• Before we can access data in the MySQL database, we need to
be able to connect to the server.
• PHP provides mysqli_connect() function to open a database
connection.
• This function takes five parameters and returns a MySQLi link
identifier on success or FALSE on failure.

6. MySQLi Connection
• Example:
<?php
$servername = “ "; // localhost
$username = “ "; // your own server username
$password = “ "; // your own server password
// Create connection
$conn = mysqli_connect($servername, $username, $password);
// Check connection
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

7. MySQLi Create/Drop Database
• PHP uses mysqli_query function to create or delete a MySQLi
database.
• This function takes two parameters and returns TRUE on
success or FALSE on failure.

8. MySQLi Create Database
• Example:
<?php
$dbhost = ‘ ';
$dbuser = ‘ ';
$dbpass = ‘ ';
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
echo 'Connected failure<br>';
}
echo 'Connected successfully<br>';
$sql = "CREATE DATABASE DB1";
if (mysqli_query($conn, $sql))
{
echo "Database created successfully";
}
else
{
echo "Error creating database: " . mysqli_error($conn);
}
mysqli_close($conn);
?>

9. MySQLi Drop Database
• Example:
<?php
$dbhost = ‘ ';
$dbuser = ‘ ';
$dbpass = ‘ ';
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
echo 'Connected failure<br>';
}
echo 'Connected successfully<br>';
$sql = “DROP DATABASE DB1";
if (mysqli_query($conn, $sql))
{
echo “Database deleted successfully";
}
else
{
echo "Error deleting database: " . mysqli_error($conn);
}
mysqli_close($conn);
?>

10. MySQLi Select Database
• Once you get connection with MySQLi server, it is required to
select a particular database to work with.
• This is because there may be more than one database
available with MySQLi Server.

11. MySQLi Select Database
• Example:
<?php
$dbhost = ‘ ';
$dbuser = ‘ ';
$dbpass = ‘ ';
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
echo 'Connected failure<br>';
}
echo 'Connected successfully<br>';
mysqli_select_db( ‘DB1' );
//Write some code here
mysqli_close($conn);
?>

12. MySQLi Create Table
• The table creation command requires:
• Name of the table
• Names of fields
• Definitions for each field
• To create new table in any existing database you would
need to use PHP function mysqli_query().
• You will pass its second argument with proper SQL
command to create a table.

13. MySQLi Create Table
• Example:
<?php
// Connection to Database
// Select Database
$sql = "CREATE TABLE table1( id INT AUTO_INCREMENT,fname VARCHAR(20) NOT
NULL,primary key (id))";
if(mysqli_query($conn, $sql))
{
echo "Table created successfully";
}
else
{
echo "Table is not created successfully ";
}
mysqli_close($conn);
?>

14. MySQLi Drop Table
• It is very easy to drop an existing MySQLi table, but you
need to be very careful while deleting any existing table
because data lost will not be recovered after deleting a
table.
• To drop an existing table in any database, you would
need to use PHP function mysqli_query().
• You will pass its second argument with proper SQL
command to drop a table.

15. MySQLi Drop Table
• Example:
<?php
// Connection to Database
// Select Database
$sql = "DROP TABLE table1";
if(mysqli_query($conn, $sql))
{
echo "Table is deleted successfully";
}
else
{
echo "Table is not deleted successfullyn";
}
mysqli_close($conn);
?>