select * from (
select A A1,B B1,C C1 from table1
union all select F,K,G from table2
union all select Q,I,E from table3
) t

------解决方案--------------------

SQL code

select A A1,B B1,C C1 from table1
union all 
select F,K,G from table2
union all 
select Q,I,E from table3