Question

如果我不理解简单的事情，那就太糟糕了，因为我刚刚开始编写SQL查询。

我有两个问题：

SELECT * FROM status WHERE author IN（SELECT user1 FROM friends WHERE user2 ='$ username'并接受='1'）或作者IN（SELECT user2 FROM friends WHERE user1 ='$ username'AND accepted ='1'）

和

SELECT * FROM status WHERE author ='$ username'

如何在SQL查询中本地或在PHP中组合这两个查询的结果？

Answer 1

尝试UNION：

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

要允许重复值，请将ALL关键字与UNION一起使用。

SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;

Answer 2

仅使用OR有什么问题？

SELECT * 
FROM status 
WHERE author IN (SELECT user1 FROM friends WHERE user2='$username' AND accepted='1') 
    OR author IN (SELECT user2 FROM friends WHERE user1='$username' AND accepted='1')
    OR author = '$username'

如何在SQL中组合两个查询的结果？

2 个答案: