oracle ORA-00907: 缺失右括号 问题已解决

问题出现情况：

 select * from

 (

select a,b,c

from tab_a

order by a

  union all

select a,b,c

from tab_b

order by a

) A;

出现如题所示的错误，

解决方式如下：

 select * from

 (

select a,b,c

from tab_a

--order by a

  union all

select a,b,c

from tab_b

    --order by a

) A order by a;

原来是union all 中出现的 "order by a"