Question

Table1 (ID, Col1, col2, col3, col4)

Table2 (ID, Col5, col6)

-----------------SP-------------------

set @Ids = '1,2,3,4,5,6,7,8,9' // Input paremeter  (can be NULL)

Create Table #Tabel2
(
     Id int
)
Insert into #table2 select * from dbo.Split(@Ids, ',')

现在#table2有：1 2 3 4 5 6 7 8 9

方案

Select t1.Col1,t1.col2,t1.col3 
FROM Table1 as t1 
  INNER JOIN Table2 as t2 ON t1.Col1=t2.Col2
    AND (@Ids is null OR t1.ID in (Select Id from #Table2))

问题

如何用条件内连接替换IN？

Answer 1

因为您使用了从未在查询中定义的别名t，所以我不清楚哪个表ID应该加入。我猜了一下并使用了t1。

Select t1.Col1,t1.col2,t1.col3 
FROM Table1 as t1 
INNER JOIN Table2 as t2 ON t1.Col1=t2.Col2 
left outer join #Table2 ids on @Ids is null or t1.ID = ids.ID --maybe this should be t2.ID = ids.ID?

Answer 2

除非我误解（毕竟是星期五下午），你想要Table1 / Table2中的所有行，尽可能匹配＃Table2，但是如果＃Table2为空，那么这只是一个外连接。 / p>

SELECT t.Col1,
       t.col2,
       t.col3
FROM   Table1 AS t1
       INNER JOIN Table2 AS t2
         ON t1.Col1 = t2.Col2
       LEFT OUTER JOIN #Table2 t3
         ON t2.ID = t3.ID

Answer 3

在SQL Server 2008中，您可以在join子句中使用CASE语句，例如：

SELECT * 
FROM table1
INNER JOIN table2 ON CASE WHEN table1.column1 = 'this' THEN null ELSE 'that' END = table2.column1

如何用条件内连接替换IN（）？

3 个答案: