The function createSequence() creates an auto-incrementing number device. If the database supports it, it uses native sequence handling routines, otherwise it emulates the functionality using a table and an auto-incrementing numbers.

Once created, numbers can retrieved using genId().

/*
 * Connection assumed
 */
 
/*
 * Create a sequence called my_sequence, using default start of 1
 */
$db->createSequence('my_sequence');