(Oracle)SQL语句的学习:键字:intersect,minus

关键字的用法，intersect（取交集），minus（取差集）

 

 (select a.name from a) intersect (select b.name from b)

 

 (select a.name from a) minus (select b.name from b)

 

 

 

避免使用	替代方法
field in(a,b,c)	field=a or field = b or field=c
field is null /is not null	field > ' ' 、field > 0
select * from a union select * from b 先取两表，再合并	select * from a union all select * from b 简单的将两个结果合并后就返回