SQLite“”运算符不起作用(SQLite “” operator not working)

SQLite“<>”运算符不起作用(SQLite “<>” operator not working)

我有这个查询：

SELECT username FROM users INNER JOIN friends WHERE friends.user_a = users.id OR friends.user_b = users.id AND users.username <> 'david';

它返回一行where users.username ='david'。 我怎么能没有这个返回？

'用户'表格结构/样本数据

'朋友'表结构/样本数据

I have this query:

SELECT username FROM users INNER JOIN friends WHERE friends.user_a = users.id OR friends.user_b = users.id AND users.username <> 'david';

It is returning a row where users.username = 'david'. How can I have this not returned?

'users' table structure/sample data

'friends' table structure/sample data

最满意答案

也许尝试NOT LIKE '%david%'的任何非打印字符？

尝试WHERE (friends.user_a = users.id OR friends.user_b = users.id) AND users.username <> 'david';

说明：你的逻辑是friends.user_a = users.id OR friends.user_b = users.id AND users.username <> 'david'你在说：“给我带任何人的朋友用user_a或者等等......”首先应用它并不需要检查其余部分，但在括号后面，我们说：“带给我任何人1.与user_a或users_b是朋友2.他的user_name不是'david'”。

Maybe try NOT LIKE '%david%' for any non-print chars?

try WHERE (friends.user_a = users.id OR friends.user_b = users.id) AND users.username <> 'david';

Explanation: Your logic was friends.user_a = users.id OR friends.user_b = users.id AND users.username <> 'david' You were saying: "bring me anyone who's friend with user_a OR etc..." so when the first applies it doesn't need to check the rest, but after the parentheses, we are saying: "Bring me anyone who 1. Is friends with user_a or users_b 2. His user_name is not 'david'".