除了一些列之外如何进行LEFT OUTER JOIN？

Question

我有3张桌子：

首先＆＃34;安置＆＃34;

第二个＆＃34; user_info＆＃34;

第三个＆＃34; user_placements＆＃34;

我想通过用户信息获取所有展示位置数据

怎么做？

我试过这个，但结果并不是我的预期：

SELECT *, user_placements.id AS user_placements_id, placement.id AS placement_id
FROM placement
LEFT OUTER JOIN user_placements ON placement.id = user_placements.id_placement

Answer 1

您需要再添加一个用户信息

SELECT placement.*,user_info.id as user_info_id,user_info.name as user_name,user_info.mobile as user_mobile
 FROM placement LEFT OUTER JOIN user_placements ON placement.id = user_placements.id_placement
    LEFT OUTER JOIN user_info ON user_info.id = user_placements.id_user

Answer 2

您缺少第二次加入：

SELECT *
FROM placement AS p
JOIN user_placements AS up ON p.id = up.id_placement
JOIN user_info AS u ON up.id_user = u.id

将通配符替换为您想要的数据。 您当然会通过此查询获得重复数据。