Question

这是我的查询，但它显示结果不是我预期的。

SELECT  
a.PROJECT_NO, 
CASE WHEN a.PROJECT_NO = b.PROJECT_NO THEN 'TRUE' ELSE 'FALSE' END AS CONDITION 
FROM PROJECT a
LEFT OUTER JOIN WORKSHEET b ON (b.PROJECT_NO = a.PROJECT_NO)

Table a                 Table b
Project_No              Project_No
1111                    1111  
2222                    3333 
3333                    
4444

正确的结果应该是

Project_No      Condition           
1111             True                
2222             FALSE               
3333             TRUE                
4444             FALSE

我的查询结果，所有条件状态显示为真

Project_No      Condition
1111             TRUE 
2222             TRUE 
3333             TRUE
4444             TRUE

任何人都可以帮我修理它。谢谢

Answer 1

a.PROJECT_NO = b.PROJECT_NO始终在null时返回b.PROJECT_NO = null，而WHEN中的第一个CASE选择返回TRUE，否则，b.PROJECT_NO时NULL由于正确的相等结果，1}}不会返回TRUE IS NULL。因此，最简单的方法是将t2.Project条件用于SELECT a.PROJECT_NO , (CASE WHEN b.PROJECT_NO IS NULL THEN 'TRUE' ELSE 'FALSE' END) AS CONDITION FROM PROJECT a LEFT OUTER JOIN WORKSHEET b ON b.PROJECT_NO = a.PROJECT_NO列：

{{1}}

Answer 2

用COALESCE

包装

COALESCE(CASE WHEN a.PROJECT_NO = b.PROJECT_NO THEN 'TRUE' END, 'FALSE')

Answer 3

您可以尝试 ISNULL

试试这个

SELECT  
a.PROJECT_NO, 
CASE WHEN (ISNULL(a.PROJECT_NO,0) = IsNULL(b.PROJECT_NO,1) THEN 'TRUE' ELSE 'FALSE' END AS CONDITION 
FROM PROJECT a
LEFT OUTER JOIN WORKSHEET b ON (b.PROJECT_NO = a.PROJECT_NO)

Answer 4

我认为这样做会让你不再需要加入

选择
a.PROJECT_NO，

当a.PROJECT_NO IN（从工作表中选择PROJECT_NO）那么＆＃39; TRUE＆＃39; ELSE＆＃39; FALSE＆＃39;结束条件

FROM PROJECT a

Answer 5

另一种方式：）

SELECT a.PROJECT_NO, 
       COALESCE (CONDITION,'FALSE') AS CONDITION FROM 
PROJECT a
OUTER APPLY
(
    SELECT 'TRUE' AS CONDITION  
    FROM WORKSHEET
    WHERE PROJECT_NO =  a.PROJECT_NO
) AS Sub

谢谢， barua.me

sql第1列和第2列包含相同的值，然后条件A，否则为B.

5 个答案: