Php 使用可选的列匹配连接2个表

一直在做一些MySQL的事情，发现了一个棘手的问题需要解决

这里有两个MySQL表

Table1: user_fav

fav_id | brand_id | Keyword
   1   |    0     | test
   2   |    67    | test1
   3   |    68    |


Table 2: products

p_id   | p_brand |   p_name
  1    |   67    | test1 shoes
  2    |   68    | test shoes

我试图找到与

user\u fav

表匹配的产品数量，如下所示：

• 如果

  brand\u id

  为0，则将

  keyword

  与

  p\u name

• 如果

  brand\u id

  >0和

  关键字！=''然后在这两种条件下加入

• 如果

  brand\u id

  >0和

  keyword=''

  则加入

  brand\u id和p\u brand

总的来说，我需要找到与

用户\u fav

行匹配的产品计数

已尝试此查询，但它只包含一个条件：

select `uf`.`fav_id`, count(`p`.`p_id`) AS `pcount` from (`user_fav` `uf` left join `products` `p` on(((`p`.`p_name` like convert(concat('%',`uf`.`keyword`,'%') using utf8))))) group by `uf`.`fav_id`

有什么建议可以解决这个问题吗

谢谢

SELECT u.*, count(p.p_id) as pcount
FROM user_fav u
JOIN products p
  ON ( u.`brand_id` = 0 and p.`p_name` Like CONCAT('%',  u.`Keyword`, '%'))
  OR ( u.`Keyword` = '' and u.`brand_id` = p.`p_brand`)  
  OR (  u.`brand_id` > 0 and u.`Keyword` <> '' and 
        ( u.`brand_id` = p.`p_brand` AND p.`p_name` Like CONCAT('%',  u.`Keyword`, '%'))
      ) group by u.fav_id

SELECT u.*, count(p.p_id) as pcount
FROM user_fav u
JOIN products p
  ON ( u.`brand_id` = 0 and p.`p_name` Like CONCAT('%',  u.`Keyword`, '%'))
  OR ( u.`Keyword` = '' and u.`brand_id` = p.`p_brand`)  
  OR (  u.`brand_id` > 0 and u.`Keyword` <> '' and 
        ( u.`brand_id` = p.`p_brand` AND p.`p_name` Like CONCAT('%',  u.`Keyword`, '%'))
      ) group by u.fav_id

---

您的连接条件不必是一对一的，因此您可以对条件进行分组，因为每个规则集都不包含下一个规则集

select 
    `uf`.`fav_id`, 
    count(`p`.`p_id`) AS `pcount` 
from 
    `user_fav` `uf` 
left join 
    `products` `p` 
    ON (
       `uf`.`brand_id` = 0
       AND `uf`.`Keyword` = `p`.`p_name`
    )
    OR (
        `uf`.`brand_id` > 0
       AND `uf`.`Keyword` != ''
       AND `uf`.`Keyword` = `p`.`p_name`
       AND `uf`.`brand_id` = `p`.`p_id`
    )
    OR (
        `uf`.`brand_id` > 0
       AND `uf`.`Keyword` = ''
       AND `uf`.`brand_id` = `p`.`p_id`
    )
group by `uf`.`fav_id`

---

您的连接条件不必是一对一的，因此您可以对条件进行分组，因为每个规则集都不包含下一个规则集

select 
    `uf`.`fav_id`, 
    count(`p`.`p_id`) AS `pcount` 
from 
    `user_fav` `uf` 
left join 
    `products` `p` 
    ON (
       `uf`.`brand_id` = 0
       AND `uf`.`Keyword` = `p`.`p_name`
    )
    OR (
        `uf`.`brand_id` > 0
       AND `uf`.`Keyword` != ''
       AND `uf`.`Keyword` = `p`.`p_name`
       AND `uf`.`brand_id` = `p`.`p_id`
    )
    OR (
        `uf`.`brand_id` > 0
       AND `uf`.`Keyword` = ''
       AND `uf`.`brand_id` = `p`.`p_id`
    )
group by `uf`.`fav_id`