Question

SELECT
    CASE 
        WHEN FIRST_NAME = 'alina' THEN (COMMISSION*RATE/TOTAL_DAYS)  
        ELSE REWARD 
    END AS reward
FROM testing;

我需要检查TOTAL_DAYS是0还是NULL。我怎样才能做到这一点？对于NULL的情况，我可以使用ISNULL函数。

但是如何检查案例0或NULL？如果TOTAL_DAYS ZERO或NULL,生成TOTAL_DAYS = 1。

Answer 1

    select 
CASE 
    WHEN FIRST_NAME = 'alina' THEN  (COMMISSION * RATE/ISNULL(NULLIF(TOTAL_DAYS, 0), 1))  
    ELSE REWARD 
end as reward
    from testing;

Answer 2

您可以结合使用NULLIF和ISNULL：

SELECT
    CASE 
        WHEN FIRST_NAME = 'alina' THEN  (COMMISSION * RATE/ ISNULL(NULLIF(TOTAL_DAYS, 0), 1))  
        ELSE REWARD 
    END ASreward
FROM testing;

如果NULLIF为NULL，TOTAL_DAYS将返回0。然后，如果ISNULL返回1，NULLIF将返回NULL。例如：

SELECT ISNULL(NULLIF(N, 0), 1) AS N
FROM(
    VALUES (3), (NULL), (0)
)t(N)

返回：

N
-----------
3
1
1

Answer 3

您可以使用coalesce将null翻译为1，将greatest翻译为0：

SELECT CASE WHEN FIRST_NAME = 'alina' 
            THEN commission * rate / GREATEST(COALESCE(total_days, 1), 1)
            ELSE reward END AS reward 
FROM testing;

Answer 4

如果有效，请检查一下。

        select 
    CASE 
        WHEN FIRST_NAME = 'alina' THEN CASE WHEN COALESCE(TOTAL_DAYS,0) = 0 THEN 0 ELSE (COMMISSION*RATE/TOTAL_DAYS)  
        ELSE REWARD 
    end as reward
        from testing;

Answer 5

试试这个：

SELECT
    CASE
    WHEN FIRST_NAME = 'alina' THEN
        commission * rate / COALESCE(NULLIF(total_days, 0), 1)
    ELSE
        reward
    END AS reward 
FROM
    testing;

在除数中检查零或NULL

5 个答案: