Allows writing SQL that works for all supported databases, without
having to deal with differences in SQL dialects.
Supported SQL categories:
- SELECT: $db->createSelectQuery();
- INSERT: $db->createInsertQuery();
- UPDATE: $db->createUpdateQuery();
- DELETE: $db->createDeleteQuery();
Query object:
- Uses a "fluent-interface"
- Exposes an expression object through $db->e.