按标签获取类似图像，但过滤具有特定类别的图像

Question

我有3张桌子

图像

    id , name 
    1  , abc

image_tags

    id , image_id , tag
    1  , 1345     , football
    2  , 1345     , sport
    3  , 1666     , football 

image_categories

    id , image_id , cat

    1  , 1345     , 7
    2  , 1345     , 3
    3  , 1666     , 8

在我的查询中，我有一系列标签，我想获得类似的图像

这很容易（我只是写了这个请求，没有提到语法错误）

select distinct(image_tags.image_id) , images.* from 
image_tags join images on image_tags.image_id = images.id 
where image_tags.tag IN (implode(',' , $tag_Array )) limit 10

但这是棘手的部分 我不想要3类图像！ 如何在同一查询中过滤类别3的图像？

Answer 1

<击> JOIN表格image_categories然后您可以按类别cat进行过滤：

SELECT DISTINCT 
  it.image_id, 
  i.* 
FROM image_tags AS it
INNER JOIN images           AS i ON it.image_id = i.id 
INNER JOIN image_categories AS c ON c.image_id  = i.id
WHERE it.tag IN (implode(',' , $tag_Array )) 
  AND c.cat <> 3
LIMIT 10;

请在此处查看：

• SQL Fiddle Demo

<击>

---

更新

使用NOT IN谓词或LEFT JOIN：

Select distinct 
  it.image_id,
  i.* 
from image_tags AS it
INNER JOIN images           AS i ON it.image_id = i.id 
WHERE it.tag IN (implode(',' , $tag_Array ))
  AND it.image_id NOT IN(SELECT image_id 
                         FROM image_categories
                         WHERE image_id <> 3
                           AND image_id IS NOT NULL)
  limit 10;

请在此处查看：

• SQL Fiddle Demo