挺怪的一个SQL
Table A
a1 NVRCHAR(10),
a2 NVRCHAR(10),
a3 NVRCHAR(10)
Table B
b1 NVRCHAR(10),
b2 NVRCHAR(10),
b3 NVRCHAR(10)
SELECT *
FROM A
INNER JOIN B
ON A.a1 = '1'
WHERE B.b1 = '2'
今天看到别人写的这个SQL，这是什么用意呢
结果是笛卡尔积吗？
[解决办法]
--> 测试数据: @TableA
declare @TableA table (a1 int,a2 int,a3 varchar(1))
insert into @TableA
select 1,2,'a' union all
select 1,3,'b' union all
select 2,2,'c' union all
select 2,3,'d' union all
select 3,1,'e' union all
select 3,3,'f'
--> 测试数据: @TableB
declare @TableB table (b1 int,b2 int,b3 varchar(1))
insert into @TableB
select 1,2,'a' union all
select 1,3,'b' union all
select 2,2,'c' union all
select 2,3,'d' union all
select 3,1,'e' union all
select 3,3,'f'
select * from @TableA a inner join @TableB b
on a.a1='1' where b.b1='2'
/*
a1 a2 a3 b1 b2 b3
----------- ----------- ---- ----------- ----------- ----
1 2 a 2 2 c
1 3 b 2 2 c
1 2 a 2 3 d
1 3 b 2 3 d
*/
