PHP与MySQL查询未返回预期结果

Question

我是PHP的新手，正在尝试选择表中的记录（用于搜索功能），该表中的月份是固定的，而其他列则有所不同。

下面是查询：

SELECT * 
FROM issue 
WHERE month = "Apr 2019" 
    AND issue LIKE "%ekh%" 
    OR issue_type LIKE "%ekh%" 
    OR facility LIKE "%ekh%" 
    OR issue_id LIKE "%ekh%" 
    OR priority LIKE "%ekh%" 
ORDER BY issue_id DESC

而是返回所有满足like子句的行，即使month isnt =“ Apr 2019”。

Answer 1

在代数中，“ AND运算先于“ OR运算。 这与您的WHERE子句中的规则相同。

您可以使用如下括号来解决此问题：

SELECT *
FROM issue
WHERE month = "Apr 2019"
    AND (issue LIKE "%ekh%"
        OR issue_type LIKE "%ekh%"
        OR facility LIKE "%ekh%"
        OR issue_id LIKE "%ekh%"
        OR priority LIKE "%ekh%")
ORDER BY issue_id DESC

Answer 2

当mysql首先命中时or它将自动返回所有内容，因为or something is true 。 因此，您应该使用括号：

SELECT *
FROM issue
WHERE month = "Apr 2019" AND
(issue like "%ekh%" OR
 issue_type like "%ekh%" OR
 facility like "%ekh%" OR
 issue_id like "%ekh%" OR
 priority like "%ekh%")
ORDER BY issue_id DESC