SQLite3

SQLite is a C-language library that implements a small, fast, self-contained, high-reliability, full-featured, SQL database engine.

The related extension is SQLite3. It allows the creation and usage of file-based or memory-based databases.

SQLite3 is also available with PDO (Portable Document File), with the pdo_sqlite engine.

<?php
$db = new SQLite3('my.sqlite3');

$results = $db->query('SELECT bar FROM foo');
while ($row = $results->fetchArray()) {
    var_dump($row);
}
?>

Documentation

See also SQLite3 in PHP and How to Store Images in SQLite with PHP.

Related : Structured Query Language (SQL), SQL Database, PHP Data Objects (PDO), Relational DataBase Management System (RDBMS)