PHP mysqli() and mysqli_connect(): Connect to the Database

This article is created to cover the two functions of PHP, namely:

• mysqli()
• mysqli_connect()

Both functions are used to open a connection to the MySQL database server. The only difference is that mysqli() uses PHP mysqli object-oriented script, whereas mysqli_connect() uses PHP mysqli procedural script to do the job.

PHP mysqli(): connect to a database using object-oriented

The PHP mysqli() function opens a connection to the MySQL database server in object-oriented style with the help of the "new" keyword. For example:

<?php
   $servername = "localhost";
   $username = "root";
   $password = "";
   $databasename = "codescracker";
   
   $conn = new mysqli($servername, $username, $password, $databasename);
   
   if($conn -> connect_errno)
   {
      echo "Failed to establish the connection to the database.<BR>";
      echo "Reason: ", $conn -> connect_error;
      exit();
   }
   else
   {
      echo "Connection established successfully!";
      
      // block of code to process further...
   }
   $conn -> close();
?>

Since root is the username of my MySQL database server. Also, I have a database named codescracker inside it. And the password for my database server is empty. Therefore, the output of the above example in my case is:

Note: The new keyword is used to create a new object.

Note: The connect_errno is used to get or return the error code (if any) from the last connect call in object-oriented style.

Note: The connect_error is used to get the error description (if any) from the last connection in object-oriented style.

Note: The exit() function is used to terminate the execution of the current PHP script.

Note: The close() function is used to close an opened connection in object-oriented style.

PHP mysqli() Syntax

The syntax of the mysqli() function in PHP to open a database connection, using object-oriented style, is:

$conn = new mysqli(host, username, password, databasename, port, socket)

Note: The $conn is the connection variable, used further to check whether the connection was established or not. If the connection has been established, then we can use this variable to work with the database named databasename.

Note: The host parameter is used to specify the host name or an IP address of the MySQL server.

Note: The username parameter is used to specify the username of the MySQL server.

Note: The password parameter is used to specify the password of the MySQL server.

Note: The databasename parameter is used to specify the name of the MySQL database to use in the program or application.

Note: The port parameter is used to specify the port number where the connection is to be attempted.

Note: The socket parameter is used to specify the socket that has to be used.

All the five parameters are optional. But the first four parameters are used most of the time.

PHP mysqli_connect(): connect to the database using procedural

The PHP mysqli_connect() function opens a connection to the MySQL database server in procedural style. For example:

<?php
   $servername = "localhost";
   $username = "root";
   $password = "";
   $databasename = "codescracker";
   
   $conn = mysqli_connect($servername, $username, $password, $databasename);
   
   if(mysqli_connect_errno())
   {
      echo "Failed to establish the connection to the database.<BR>";
      echo "Reason: ", mysqli_connect_error();
      exit();
   }
   else
   {
      echo "Connection established successfully!";
      
      // block of code to process further...
   }
   mysqli_close($conn);
?>

Note: The mysqli_connect_errno() function is used to get or return the error code (if any) from the last connect call in procedural style.

Note: The mysqli_connect_error() function is used to return the error description (if any) from the last connection in procedural style.

Note: The mysqli_close() function is used to close an opened connection to the MySQL database in procedural style.

PHP mysqli_connect() Syntax

The syntax of the mysqli_connect() function in PHP to open or establish a connection to the MySQL database, in MySQLi procedural, is:

$conn = mysqli_connect(host, username, password, databasename, port, socket)

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