选择LEFT JOIN和WHERE CLAUSE

Question

我有2个表：用户{用户名，用户ID}和奖品{用户ID，奖品，状态}

我想选择所有用户（来自用户左加入奖品），但在奖品表中有'status = dead'的用户除外

Answer 1

我认为您需要INNER JOIN，因为您只想搜索状态不等于dead的用户。

SELECT  a.*, b.*
FROM    Users a
        INNER JOIN Prizes b
            ON a.userID = b.UserID
WHERE   b.status <> 'dead'

要进一步了解联接，请访问以下链接：

• Visual Representation of SQL Joins

更新1

SELECT  a.*, b.*
FROM    Users a
        LEFT JOIN Prizes b
            ON a.userID = b.UserID
WHERE   b.UserID IS NULL OR b.status <> 'dead'

Answer 2

试试这个;

select u.* 
from users as u 
left join prizes as p 
on u.userid = p.userid 
where p.status <>'dead';

由于