Why Should I Migrate from MySQL Functions to PDO?

How to Migrate from MySQL Functions to PDO

Introduction

As PHP 5.5.0 marks the deprecation of MySQL functions, it's essential to transition to alternatives like PDO or MySQLi for database operations. This article provides a guide for migrating your code to PDO, covering both MySQL and MSSQL servers.

Why MySQL Functions are Deprecated

MySQL functions are old and prone to security vulnerabilities, making them unsuitable for modern PHP applications. They lack convenience features and are difficult to apply securely. PDO and MySQLI address these issues and offer significant improvements.

Connecting to MySQL with PDO

1. The PHP module php_pdo_mysql.dll is required.

2. Create a PDO instance using the DSN (Data Source Name):

   • $dsn = 'mysql:dbname=databasename;host=127.0.0.1';
   • $dbh = new PDO($dsn, $user, $password);

Connecting to MSSQL with PDO

1. Install php_pdo_sqlsrv_##_ts.dll or php_pdo_sqlsrv_##_nts.dll drivers.

2. Create a PDO instance using the DSN (Data Source Name):

   • $dsn = 'sqlsrv:Server=127.0.0.1;Database=databasename';
   • $dbh = new PDO($dsn, $user, $password);

Performing Queries with Prepared Statements

PDO uses prepared statements that prevent SQL injection by sanitizing user input inserted into SQL queries. To prepare a statement:

1. Use ->prepare() to create a prepared statement.

   • $SQL = 'SELECT ID, EMAIL FROM users WHERE user = :username';
   • $stmt = $dbh->prepare($SQL);

2. Bind parameter(s) to the prepared statement using ->bindValue():

   • $stmt->bindValue(':username', $username);

Executing Queries

1. Execute the prepared statement using ->execute() without passing any arguments:

   • $stmt->execute();

2. For direct queries, use ->query():

   • $result = $dbh->query($SQL);

Fetching Results

fetch() fetches a single row from the result set. fetchAll() fetches all rows into an array.

Sample Class for PDO

class pdoConnection {
    // ...
    public function prepare($SQL, $params = array()) {
        $result = $this->connection->prepare($SQL);
        $result->execute($params);
        return $result;
    }
}

// Usage:
$SQL = 'SELECT ID, EMAIL FROM users WHERE user = :username';
$result = $db->prepare($SQL, array(":username" => 'someone'));

Conclusion

Migrating to PDO from MySQL functions requires some code modifications, but it significantly improves database security and prepares your application for future PHP versions. The provided code samples and sample class should assist in a smooth transition.

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