Part 6.1Getting started with MySQL in PHP

This part of the tutorial will cover how to use MySQL with PHP. It will use some very basic SQL commands to demonstrate results. It will not however, go into much detail about MySQL. The MySQL tutorial is a better place to start for this.

This article assumes that a user name and login for a server with MySQL are both available.

This article also uses the newer MySQLi driver.

Connecting

The first thing that is necessary for PHP to be able to use MySQL with PHP is to connect to the MySQL system. With MySQLi and PHP, this is done using the mysqli_connect function.

<?php
	//Use the following command to connect
	$myConnection = mysqli_connect($dbName, $dbUsername, $dbPassword);
?>
		

It is important with MySQLi that all connections are saved into variables as they are required with nearly every MySQLi command.

It may also be a good idea to check that the connection succeeded:

<?php
	//Use the following command to connect
	$myConnection = mysqli_connect($dbName, $dbUsername, $dbPassword);
	//If there are any errors producing an error number
	if(mysqli_connect_errno()) {
		echo "Failed to connect!";
		exit();
	}
?>
		

Selecting the default database

Whilst this step is not entirely necessary, if PHP only needs to access one database it may be a good idea to select the default database. This means that queries do not need the name of the database included in them. This is achieved with the mysqli_select_db function.

<?php
	//Select the database stored in $myDB
	mysqli_select_db($myConnection, $myDB);
?>
		

Note that the $myConnection variable has been given as the first parameter. PHP requires that this is given to any MySQLi functions.

Running queries

Of course the most important thing about MySQL is being able query the database. PHP allows this through the mysqli_query function:

<?php
	//Query the database
	$result = mysqli_query($myConnection, $query);
?>
		

The query should also be tested to make sure that it worked:

<?php
	//Query the database
	$result = mysqli_query($myConnection, $query);
	if($result)
		echo "Success!";
	else
		echo "Failure!";
?>
		

Closing the connection

It is very important that the connection is closed once it is finished with. PHP keeps the connection open whilst that script is still running to support connection pooling but this wastes resources if only one query is required. PHP uses the mysqli_close function to close a connection:

<?php
	mysqli_close($myConnection);
?>