以下哪项是UNION操作符的正确用法?( )
SELECT * FROM UNION TableA, TableB
SELECT * FROM TableA UNION SELECT * FROM TableB
SELECT * FROM Table A UNION TableB
SELECT UNION * FROM TableA, TableB
以下哪项是UNION操作符的正确用法?( )
SELECT * FROM UNION TableA, TableB
SELECT * FROM TableA UNION SELECT * FROM TableB
SELECT * FROM Table A UNION TableB
SELECT UNION * FROM TableA, TableB