mysql - 什么时候用 AND？

Question

我想将 Case When 与 AND 条件一起使用，但它没有正确计算总和。

例如:

SELECT DATE(`SubmitDate`), 
     SUM(CASE status WHEN 'New' AND `Type` = 'consumer' THEN 1 ELSE 0 END) as new_consumer,
     SUM(CASE status WHEN 'New' AND `Type` = 'business' THEN 1 ELSE 0 END) as new_business
FROM report
WHERE `source` = 'net'
group by DATE(`SubmitDate`) Order by `SubmitDate` DESC

Answer 1

您需要使用 CASE WHEN [Condition] THEN... 而不是简单的 case 表达式:

SELECT DATE(`SubmitDate`), 
     SUM(CASE WHEN status = 'New' AND `Type` = 'consumer' THEN 1 ELSE 0 END) as new_consumer,
     SUM(CASE WHEN status = 'New' AND `Type` = 'business' THEN 1 ELSE 0 END) as new_business
FROM report
WHERE `source` = 'net'
group by DATE(`SubmitDate`) Order by `SubmitDate` DESC