How to Migrate from MySQL Functions to PDO_MySQL?

How to Replace MySQL Functions with PDO

MySQL functions are now deprecated and will be removed in future PHP versions. MySQLi or PDO_MySQL should be used instead.

PDO Implementation

PDO provides a consistent interface for connecting to different databases, including MySQL and MSSQL.

Connection:

• MySQL:

  $dsn = 'mysql:dbname=databasename;host=127.0.0.1';
  $dbh = new PDO($dsn, 'dbuser', 'dbpass');

• MSSQL:

  $dsn = 'sqlsrv:Server=127.0.0.1;Database=databasename';
  $dbh = new PDO($dsn, 'dbuser', 'dbpass');

Performing Queries:

PDO uses prepared statements, which prevent SQL injection vulnerabilities.

$SQL = 'SELECT ID, EMAIL FROM users WHERE user = :username';

Executing Queries:

Use prepare and execute for variable queries.

$query = $dbh->prepare($SQL);
$query->execute([':username' => 'someone']);

Fetching Results:

Use fetch or fetchAll to retrieve results.

while ($row = $query->fetch()) {
    echo $row['ID'], $row['EMAIL'];
}

Exception Handling:

Enable PDO exception handling.

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

Convenience Class:

class PDOConnection {
    function __construct($dsn, $username, $password) {
        $this->connection = new PDO($dsn, $username, $password);
        $this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->connection->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
    }

    function query($SQL) { return $this->connection->query($SQL); }
    function prepare($SQL, $params = []) { return $this->connection->prepare($SQL)->execute($params); }
}

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