1.select * from a minus select * from b3.select * from a where not exists(select * from b where a.col1=b.col1 and a.col2=b.col2...)4.select * from b minus select * from a
(select * from a minus select * from b) union (select * from b minus select * from a)
select * from( ( (select * from a minus select * from b) union (select * from b minus select * from a) ) minus ( (select * from a minus select * from b) intersect (select * from b minus select * from a) ));
谢谢 bzszp(SongZip)大哥,我明白点了。
(select * from a minus select * from b) intersect (select * from b minus select * from a) 不是空吗?
minus
select * from b
minus
select * from b3.select * from a where not exists(select * from b where a.col1=b.col1 and a.col2=b.col2...)4.select * from b
minus
select * from a
union
(select * from b minus select * from a)
(
(select * from a minus select * from b)
union
(select * from b minus select * from a)
)
minus
(
(select * from a minus select * from b)
intersect
(select * from b minus select * from a)
));
intersect
(select * from b minus select * from a)
不是空吗?
union部分:(A-B)|(B-A)=(A|B)-(A&B)
而intersect部分:(A-B)&(B-A)=空集
减去空集有什么用啊?!