sql server sql case

Question

什麼是=1在這裏做？

SELECT TOP 3 
     NewsId, 
     NewsTitle, 
     NewsContent 
    FROM disc_News 
WHERE CASE 
     WHEN DatePublish IS NOT NULL and DateExpired IS NOT NULL THEN 1 
     ELSE 0 
     END = 1 

Answer 1

1只是使整個表達式評估爲真或假。 where子句應該用於評估布爾表達式，否則您將會遇到語法錯誤

Answer 2

它會讓您獲取DatePublish和DateExpired爲NOT NULL的記錄。

Answer 3

以下WHERE條款應相當於

WHERE DatePublish IS NOT NULL 
    AND DateExpired IS NOT NULL