"=" 和 "like"

[supsuccess]

declare @v1 varchar(2),@v2 varchar(2)
declare @v3 char(2),@v4 char(2)
select @v1='1',@v2='1 ',@v3='1',@v4='1 '
select datalength(@v1)Lenth_of_v1,datalength(@v2)Lenth_of_v2,datalength(@v3)Lenth_of_v3,datalength(@v4)Lenth_of_v4
select case when @v1=@v2 then '@v1=@v2' else '@v1<>@v2' end as Comp_v1_v2 ,
case when @v3=@v4 then '@v3=@v4' else '@v3<>@v4' end as Comp_v3_v4
select case when @v1 like @v2 then '@v1 like @v2' else '@v1 not like @v2' end as v1_Like_v2 ,
case when @v3 like @v4 then '@v3 like @v4' else '@v3 not like @v4' end as v3_Like_v4

1.为什么@v1=@v2 ?
2.为什么@v1 not like @v2 ?

[supsuccess]

资料上的解释:
其原因可能是--
ANSI SQL的填充规则要求两个比较是否相等的字符串在比较之前填充程同样长度,对LIKE则不然.

[Yang_]

supsuccess(口气不小)说的对！

[supsuccess]

既然没有人关注,那么就结帖!

[neosu]

我这运行的结果

Lenth_of_v1 Lenth_of_v2 Lenth_of_v3 Lenth_of_v4
----------- ----------- ----------- -----------
1 2 2 2

（所影响的行数为 1 行）

Comp_v1_v2 Comp_v3_v4
---------- ----------
@v1=@v2 @v3=@v4

（所影响的行数为 1 行）

v1_Like_v2 v2_Like_v1 v3_Like_v4
---------------- ---------------- ----------------
@v1 not like @v2 @v2 like @v1 @v3 like @v4

（所影响的行数为 1 行）

[supsuccess]

大家以后可要注意呀!

[Yang_]

这个测试很有意思！

declare @v1 varchar(2),@v2 varchar(2)
declare @v3 char(2),@v4 char(2)
select @v1='1',@v2='1 ',@v3='1',@v4='1 '
select datalength(@v1)Lenth_of_v1,datalength(@v2)Lenth_of_v2,datalength(@v3)Lenth_of_v3,datalength(@v4)Lenth_of_v4
select case when @v1=@v2 then '@v1=@v2' else '@v1<>@v2' end as Comp_v1_v2 ,
case when @v3=@v4 then '@v3=@v4' else '@v3<>@v4' end as Comp_v3_v4
select case when @v1 like @v2 then '@v1 like @v2' else '@v1 not like @v2' end as v1_Like_v2 ,
case when @v2 like @v1 then '@v2 like @v1' else '@v2 not like @v1' end as v2_Like_v1 ,
case when @v3 like @v4 then '@v3 like @v4' else '@v3 not like @v4' end as v3_Like_v4

结果：
@v1 not like @v2
@v2 not like @v1

[Yang_]

上面的贴错了，发现csdn一旦按了“发出回复”就取消不了！

这个测试很有意思！

declare @v1 varchar(2),@v2 varchar(2)
declare @v3 char(2),@v4 char(2)
select @v1='1',@v2='1 ',@v3='1',@v4='1 '
select datalength(@v1)Lenth_of_v1,datalength(@v2)Lenth_of_v2,datalength(@v3)Lenth_of_v3,datalength(@v4)Lenth_of_v4
select case when @v1=@v2 then '@v1=@v2' else '@v1<>@v2' end as Comp_v1_v2 ,
case when @v3=@v4 then '@v3=@v4' else '@v3<>@v4' end as Comp_v3_v4
select case when @v1 like @v2 then '@v1 like @v2' else '@v1 not like @v2' end as v1_Like_v2 ,
case when @v2 like @v1 then '@v2 like @v1' else '@v2 not like @v1' end as v2_Like_v1 ,
case when @v3 like @v4 then '@v3 like @v4' else '@v3 not like @v4' end as v3_Like_v4

结果：
@v1 not like @v2
@v2 like @v1

[supsuccess]

海兄,果然更有意思了:)

[supsuccess]

别走,解释解释呀!!!

[AWP365]

等号是忽略空格的
like相反

[china_hfz]

不错，收藏。