PHP MySQLi mysqli_connect_errno()

mysqli_connect_errno()

The mysqli_connect_errno() function returns the error code from the last connection error, if one exists.

EXAMPLE

<?php
$server = "localhost";
$username = "root";
$password = "";
$database = "mysqli_db"; // INTENTIONAL ERROR: The correct database is 'mysqli_database'

// Attempting connection
$connection = mysqli_connect($server, $username, $password, $database);

// If the function returns anything other than 0, the error output is executed
// NOTE: Since the database mysqli_db does not exist, the function 
// mysqli_connect_errno() will return the error number (code 1049). 
// The script will therefore jump to the first block and output this exact number.
if (mysqli_connect_errno()) {
    echo "Connection error number: " . mysqli_connect_errno();
} else {
    echo "Connection was established without errors.";
}

mysqli_close($connection);
?>

RESULT

The result will be displayed here...

Practical use: This function is primarily useful for automated error handling, as it only returns a number (e.g., 1045 for an incorrect password). Test it at home like this:

If the returned value is 0, it means no error occurred.

Numerical codes are standard and can be looked up in the MySQL documentation.

It is typically used together with mysqli_connect_error() for a comprehensive output.