MySQL不在或值= 0? [英] mysql not in or value=0?

问题描述

一个数据库称为小部件，它具有"id"和"title".数据库2称为小部件布局，它具有模块ID"，小部件ID"，位置"和重量".

Database one is called widgets, it has "id" and "title". Database two is called widget-layouts and it has "module-id", "widget-id", "position", and "weight".

我想做的是检查widget-layout.widget-id中是否存在widgets.id，如果存在，那么widget-layouts.position =0.我还想获取widgets的值在小部件布局中不存在.

What I am trying to do is check to see if widgets.id exists in widget-layout.widget-id and if it does, then does widget-layouts.position = 0. I also want to get the values of widgets that don't exist in widget-layouts.

这是我一直在使用的mysql查询.

Here is the mysql query I have been working with.

选择*从小部件，小部件布局 在哪里(widge-layouts.position ='0' AND widgets.id = widget-layouts.widget-id)或 widgets.id不在(选择*从 小部件布局)

SELECT * FROM widgets, widget-layouts WHERE (widge-layouts.position = '0' AND widgets.id = widget-layouts.widget-id) OR widgets.id NOT IN (SELECT * FROM widget-layouts)

通过此查询，我得到了大量的小部件列表，其中每个小部件都会显示多次.

With this query I am getting a huge list of widgets where each widget is displayed multiple times.

对此有什么想法吗?

推荐答案

 SELECT *
 FROM widgets AS w
     LEFT JOIN widget-layouts AS wl
         ON w.id = wl.widget-id
 WHERE wl.widget-id IS NULL
     OR wl.position = '0'      

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