MySQL 查询多个 where 返回 null

Question

我的以下查询对于设置和预算都返回 null。

但是，如果我删除值 11 之后的所有内容，它就会起作用。

有人知道这是怎么回事吗？

SELECT  SUM(setup_fee) AS setup, 
        SUM(budget) AS budget 
FROM gdn 
WHERE client = 11 
AND start_date BETWEEN 2017-03-26 AND 2017-04-30 
AND end_date BETWEEN 2017-03-26 AND 2017-04-30

Answer 1

您的问题既不是缺少分组依据，也不是条件周围的括号，而是您必须引用这些日期值:

SELECT  SUM(setup_fee) AS setup, 
        SUM(budget) AS budget 
FROM    gdn 
WHERE   client = 11 
        AND start_date BETWEEN '2017-03-26' AND '2017-04-30'
        AND end_date BETWEEN '2017-03-26' AND '2017-04-30'

您可以看到复制的问题的简化版本 here