mysql在一個查詢中有多個計數

Question

SELECT SUM( CASE WHEN is_half = 1 THEN 1 ELSE 0 END ) halfCount, SUM( CASE 
WHEN is_half = 0 THEN 1 ELSE 0 END ) totalCount FROM employee_leave WHERE 
YEAR(leave_date_from) = YEAR(CURRENT_DATE()) AND employee_id="EMP12" AND 
leave_status=1

通過此查詢，我得到的結果為（如果沒有值）：

halfCount | totalCount
NULL      | NULL

如何獲得0而不是NULL？

所需的輸出：

halfCount | totalCount
0         | 0

Answer 1

假設查詢正確，則可以使用COALESCE將null更改為0 （或任何其他數字）

SELECT COALESCE(SUM( CASE WHEN is_half = 1 THEN 1 ELSE 0 END ), 0) as 'halfCount',
COALESCE(SUM( CASE WHEN is_half = 0 THEN 1 ELSE 0 END ), 0) as 'totalCount'
FROM employee_leave
WHERE YEAR(leave_date_from) = YEAR(CURRENT_DATE()
     AND employee_id="EMP12"
     AND leave_status=1

我不確定這是否沒有錯誤，因為我無法在我的機器上對其進行測試，但這就是如何使用COALESCE

Answer 2

嘗試這個

SELECT IFNULL(SUM( CASE WHEN is_half = 1 THEN 1 ELSE 0 END ),0) halfCount, IFNULL(SUM( CASE 
WHEN is_half = 0 THEN 1 ELSE 0 END ),0) totalCount FROM employee_leave WHERE 
YEAR(leave_date_from) = YEAR(CURRENT_DATE()) AND employee_id="EMP12" AND 
leave_status=1