:original_name: ddm-08-0011.html .. _ddm-08-0011: SELECT UNION Syntax =================== Common Syntax ------------- .. code-block:: SELECT ...UNION [ALL | DISTINCT] SELECT ...[UNION [ALL | DISTINCT] SELECT ...] Example ------- .. code-block:: select userid from user union select orderid from ordertbl order by userid; select userid from user union (select orderid from ordertbl group by orderid) order by userid; Syntax Restrictions ------------------- SELECT statements in UNION do not support duplicate column names.