Question

这是代码

DECLARE @List TABLE (n nvarchar(50));

INSERT INTO @list (n) VALUES ('A'),('B'),('C'),('D'),('E');

SELECT 
  (t1.n ) 
  + (t2.n) 
  + (t3.n) 
  + (t4.n) 
  +(t5.n) 
FROM @list AS t1
JOIN @list AS t2 
    ON 1=1
JOIN @list AS t3 
    ON 1=1
JOIN @list AS t4 
    ON 1=1
JOIN @list AS t5 
    ON 1=1 
WHERE
    not  t1.n = t2.n 
    and not t1.n = t3.n  
    and not t1.n = t4.n 
    and not t1.n = t5.n
    and not t2.n = t3.n  
    and not t2.n = t4.n 
    and not t2.n = t5.n
    and not t3.n = t4.n 
    and not t3.n = t5.n
    and not t4.n = t5.n

我需要简化where子句，如（其中T1.n，T2.n，T3.n，.T4.n，T5.n彼此不相同）

提前致谢

Answer 1

您可以查看您拥有的不同值：

where (
  select count(distinct n)
  from (values (t1.n), (t2.n), (t3.n), (t4.n), (t5.n)) as ns (n)
) = 5

如果您的值不足5个，则某些值相等。

SQL Fiddle

Answer 2

你可以使用，

NOT IN (....)条款

像，

where t1.n NOT IN (t2.n, t3.n, t4.n,  t5.n)
and   t2.n NOT IN (t3.n , t4.n,t5.n)
and   t3.n NOT IN  (t4.n,t5.n)

Answer 3

要创建组合（或者是排列吗？），您可以使用CTE。

例如：

;with cte as
(
select n from @list
union all
select convert(nvarchar(50),L.n+ cte.n) from @List L 
    inner join cte on charindex(l.n,cte.n)=0
where LEN(l.n)<5

)
    select * from cte where LEN(n)=5

是否有任何简短的方法来编写冗长的where子句

3 个答案: