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

使用此查询，我得到的结果为（如果没有值）：

halfCount | totalCount
NULL      | NULL

如何获得0而不是NULL？

期望的输出：

halfCount | totalCount
0         | 0

Answer 1

假设您的查询正确，您可以使用COALESCE将null更改为0 （或任何其他数字）

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

我不确定这是否没有错误，因为我无法在我的机器上测试它，但这是如何使用COALESCE

Answer 2

试试这个

npm run watch

mysql在单个查询中多次计数

2 个答案: