How to Effectively Migrate from MySQL to MySQLi?

Converting MySQL to MySQLi

Based on the provided code, it may initially seem as simple as replacing mysql_query($sql); with mysqli_query($sql);. However, for a complete conversion to MySQLi, further modifications are necessary.

Function Replacements:

The first step is to replace each mysql_* function with its corresponding mysqli_* counterpart. The MySQLi Extension Function Summary provides a comprehensive listing for this purpose.

• mysql_connect -> mysqli_connect
• mysql_error -> mysqli_error or mysqli_connect_error
• mysql_query -> mysqli_query

Database Selection:

Unlike MySQL, MySQLi allows you to specify the database when connecting using the fourth parameter to mysqli_connect. Alternatively, you can still use the mysqli_select_db function if preferred.

Additional Considerations:

• Some functions have slightly different parameter requirements. Check the function summaries carefully.
• As both MySQL and MySQLi are based on libmysql, parameter differences are minimal.

Example:

Here's the provided code converted to MySQLi:

// Header file with the database configuration
$DB['dbName'] = "emails";
$DB['host'] = "localhost";
$DB['user'] = "root";
$DB['pass'] = "";

// Establish a connection to the database
$link = mysqli_connect($DB['host'], $DB['user'], $DB['pass'], $DB['dbName']);

// Query execution function
function executeQuery($sql) {
    $result = mysqli_query($link, $sql);
    if (mysqli_error($link)) {
        $error = '<BR><center><font size="+1" face="arial" color="red">An Internal Error has Occured.<BR> The error has been recorded for review</font></center><br>';
        if ($_SESSION['auto_id'] == 1) {
            $sql_formatted = highlight_string(stripslashes($sql), true);
            $error .= '<b>The MySQL Syntax Used</b><br>' . $sql_formatted . '<br><br><b>The MySQL Error Returned</b><br>' . mysqli_error($link);
        }
        die($error);
    }
    return $result;
}

// Example query
$sql = 'SELECT auto_id FROM friend_reg_user WHERE auto_id=' . $info['auto_id'];
$result_member = executeQuery($sql);
if ($line_member = mysqli_fetch_array($result_member)) {
    extract($line_member);
} else {
    header("location: index.php");
    exit;
}
?>

Once the conversion is complete, test your script to ensure everything is functioning correctly.

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