1、触发器中有deleted临时表
2、
declare @a table(a int,b int)
declare @b table(a int,b int)
insert @a values(1,1)
insert @a values(2,2)
insert @b values(1,1)
insert @b values(3,3)--左:
select * from @a Aa left join @b Bb on Aa.a=Bb.a
--右:
select * from @a Aa right join @b Bb on Aa.a=Bb.a
--内
select * from @a Aa join @b Bb on Aa.a=Bb.a
--外
select * from @a Aa full join @b Bb on Aa.a=Bb.a
--完全
select * from @a,@b
2、
declare @a table(a int,b int)
declare @b table(a int,b int)
insert @a values(1,1)
insert @a values(2,2)
insert @b values(1,1)
insert @b values(3,3)--左:
select * from @a Aa left join @b Bb on Aa.a=Bb.a
--右:
select * from @a Aa right join @b Bb on Aa.a=Bb.a
--内
select * from @a Aa join @b Bb on Aa.a=Bb.a
--外
select * from @a Aa full join @b Bb on Aa.a=Bb.a
--完全
select * from @a,@b
declare @left table(a varchar(10),b varchar(10))
declare @right table(b varchar(10),c varchar(10))insert @left select 'qw','ww'
insert @left select 'hw','ww'
insert @left select 'io','oo'
insert @left select 'vt','tt'
insert @right select 'ww','wonoo'
insert @right select 'tt','tnwei'
insert @right select 'tt','ehherh'
insert @right select 'dd','dwogjeo'select * from @left
select * from @rightselect * from @left a left join @right b on a.b = b.b
select * from @left a right join @right b on a.b = b.b
select * from @left a inner join @right b on a.b = b.b
select * from @left a full join @right b on a.b = b.b
左连 A所有记录 , B与A.相关记录(没有则null)
右边 B所有记录 , A与B.相关记录(没有则null)
Full 外连 A所有记录+B.所有记录双方没有则 null