PHP與MySQL查詢未返回預期結果

Question

我是PHP的新手，正在嘗試選擇表中的記錄（用於搜索功能），該表中的月份是固定的，而其他列則有所不同。

下面是查詢：

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

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

Answer 1

在代數中，“ AND運算先於“ OR運算。 這與您的WHERE子句中的規則相同。

您可以使用如下括號來解決此問題：

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

當mysql首先命中時or它將自動返回所有內容，因為or something is true 。 因此，您應該使用括號：

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