MySQL AND或AND的多对多条件 [英] MySQL Many-To-Many condition which combine AND/OR

问题描述

我在使用mysql查询时遇到问题，这是与

I have a problem with mysql query, it's complex problem which relates to Mysql join query for multiple "tags" (many-to-many relationship) that matches ALL tags?

所以我有经典的MN表架构:

So I have classic MN table schema:

Item
1 | Item1
2 | Item2
...

Category
1 | Category1
2 | Category2
3 | Category3
4 | Category4
...

Item_has_category
1 | 1
...

问题是-如何获得行，其中 item 具有 Category1 OR Category2 AND Category3 ?

And question is - How can I get rows, where item has Category1 OR Category2 AND Category3?

它用于某些复杂的过滤器，并且某些类别具有特殊的组，必须与 AND 一起使用.

It is for some complex filter and some categories has a special group, which must be with AND.

我想我必须将HAVING与DISTINCT (链接到顶部的其他问题)结合起来，但是我不确定如何.

I suppose that I must combine HAVING with DISTINCT (link to another questions at top), but I'm not sure how.

推荐答案

此group by将起作用:

select  ItemId
from    Item_has_category
group by
        ItemId
having  sum(case when CategoryId = 1 then 1 end) = 1
        or sum(case when CategoryId = 2 then 1 end) = 1
        andsum(case when CategoryId = 3 then 1 end) = 1 

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