SELECT * FROM a WHERE NOT EXISTS (SELECT * FROM b WHERE b.a_id = a.id)
select * from a left join b on b.id=a.id where b.id is null
a表和b表结构完全一样吗,一样的话: SELECT * FROM a WHERE NOT EXISTS (SELECT 1 FROM b WHERE b.a_id = a.id) /*去掉b表的a表数据*/ union all select * from b /*b表数据*//*或使用以下语句:假设要显示的数据字段名为:sj,下面的decode语句可以实现*/ SELECT a.id,decode(b.sj,'',a.sj,b.sj) 数据 FROM a,b where a.id=b.id(+)但是建议,如果a,b数据一样,只是为了消除重复的话可以用distinct
FROM a
WHERE NOT EXISTS (SELECT *
FROM b
WHERE b.a_id = a.id)
left join b
on b.id=a.id
where b.id is null
SELECT * FROM a
WHERE NOT EXISTS (SELECT 1 FROM b WHERE b.a_id = a.id) /*去掉b表的a表数据*/
union all
select * from b /*b表数据*//*或使用以下语句:假设要显示的数据字段名为:sj,下面的decode语句可以实现*/
SELECT a.id,decode(b.sj,'',a.sj,b.sj) 数据 FROM a,b where a.id=b.id(+)但是建议,如果a,b数据一样,只是为了消除重复的话可以用distinct