SQL和不取，或不給予正確的結果

Question

在簡單MS SQL查詢IAM無法得到結果

SELECT * FROM tblActivityTracker 
WHERE (WoM IN (NULL, 2)) 
AND (DateName = DATENAME(weekday, GETDATE())) 

PLS建議

Answer 1

你不能IN子句中使用null。

查詢

SELECT * FROM tblActivityTracker 
WHERE (WoM IN (2) OR Wom is null) -- or Wom = 2 instead of using IN 
AND (DateName = DATENAME(weekday, GETDATE())); 

Answer 2

試試這個

SELECT * FROM tblActivityTracker 
WHERE (WoM =2 OR Wom IS NULL) 
AND (DateName = DATENAME(weekday, GETDATE())); 

或者試試這個

SELECT * FROM tblActivityTracker 
WHERE (WoM in('NULL','2')) 
AND (DateName = DATENAME(weekday, GETDATE())); 

Answer 3

你能做的最好的是使用ISNULL

SELECT * FROM tblActivityTracker 
WHERE isnull(WoM,'') IN ('', '2') 
AND DateName = DATENAME(weekday, GETDATE()) 

個

Answer 4

感謝的建議...... 其實下面的查詢幫助

SELECT * FROM tblActivityTracker 
WHERE (WoM IN (2)) AND (DATENAME(weekday, GETDATE()) = DateName) OR 
    (WoM IS NULL) AND (DATENAME(weekday, GETDATE()) = DateName)