我如何在sql server的where條件中使用case語句

Question

我有這個代碼。 我想在WHERE子句中使用CASE語句，但它不會運行：

SELECT 
    pdc_distribution,
    pdc_refund,pdc_type,
    pdc_amount 
FROM user_pdc_informations 
WHERE 
    (
        CASE WHEN pdc_type='D' 
            THEN (created_at BETWEEN 1583951400 AND 1584037799) 
            ELSE 1  
        END  
    ) 
    AND sport_id = 4 
    AND user_id = 7 
    AND match_id = 29743945

如何在此查詢中使用 case 條件？

Answer 1

考慮使用OR代替：

SELECT 
    pdc_distribution,
    pdc_refund,pdc_type,
    pdc_amount 
FROM user_pdc_informations 
WHERE 
    (pdc_type <> 'D' OR created_at BETWEEN 1583951400 AND 1584037799)
    AND sport_id = 4 
    AND user_id = 7 
    AND match_id = 29743945

Answer 2

您可以使用布爾邏輯：

( (pdc_type = 'D' and created_at >= 1583951400  and created_at <= 1584037799) or
  (pdc_type <> 'D' and created_at = 1)
) 

Answer 3

CASE表達式產生值，而不是代碼。 在WHERE子句中，這意味着結果應該是與其他內容進行比較的一側。 在這種情況下，根本不需要CASE 。

SELECT 
    pdc_distribution,
    pdc_refund,pdc_type,
    pdc_amount 
FROM user_pdc_informations 
WHERE  (created_at BETWEEN 1583951400 AND 1584037799 OR pdc_type <> 'D')
    AND sport_id = 4 
    AND user_id = 7 
    AND match_id = 29743945

但也要顯示 CASE 表達式的正確用戶：

SELECT 
    pdc_distribution,
    pdc_refund,pdc_type,
    pdc_amount 
FROM user_pdc_informations 
WHERE 
   1 = CASE WHEN pdc_type = 'D' AND created_at BETWEEN 1583951400 AND 1584037799 THEN 1
           WHEN pdc_type = 'D' AND created_at NOT BETWEEN 1583951400 AND 1584037799 THEN 0
        ELSE 1 END
    AND sport_id = 4 
    AND user_id = 7 
    AND match_id = 29743945

幫助編寫有效 case 表達式的一種方法是考慮結果的數據類型。 它是一個varchar嗎？ 整數？ 不要嘗試使用布爾值。

Answer 4

應該是這樣的：

SELECT
    pdc_distribution
    ,pdc_refund
    ,pdc_type
    ,pdc_amount 
FROM 
    user_pdc_informations 
WHERE 
    created_at BETWEEN CASE WHEN pdc_type='D'  THEN 1583951400 ELSE 1 END AND CASE WHEN pdc_type='D'  THEN 1584037799 ELSE 1 END
    AND sport_id =4 
    AND user_id = 7 
    AND match_id=29743945