Mysql select where t4.name=x 并且 t2 或 t3 有一个 t1.user ！？ :)

Question

为了解释我的问题，让我们想象 4 个表。

users - (userid, user.data)

buy - (buyid, productid, userid, buy.conditions)

sell - (sellid, productid, userid, sell.conditions)

产品 - (productid, Product.data)

我想做一个选择，当有用户购买或出售名称上带有 X 的产品时，返回所有用户和产品数据。

SELECT userid, 
       USER.DATA, 
       productid, 
       product.DATA 
FROM   users, 
       buy, 
       sell, 
       products 
WHERE  ( buy.userid = users.userid 
          OR sell.userid = users.userid ) 
       AND ( buy.productid = product.productid 
              OR buy.productid = product.productid ) 
       AND product.DATA LIKE '%x%'  

这行不通，但我相信你明白我想要做什么。

Answer 1

尝试像下面这样的联合：

SELECT userid, 
       USER.DATA, 
       productid, 
       product.DATA 
FROM   users, 
       buy, 
       products 
WHERE  (buy.userid = users.userid) 
  AND  (buy.productid = product.productid)
  AND  product.DATA LIKE '%x%'  
UNION 
SELECT userid, 
       USER.DATA, 
       productid, 
       product.DATA 
FROM   users, 
       sell, 
       products 
WHERE  (sell.userid = users.userid ) 
  AND  (sell.productid = product.productid ) 
  AND  product.DATA LIKE '%x%'  

Answer 2

非常感谢大家！

在朋友的帮助下最终做了这样的事情：

SELECT USER.DATA, 
      product.DATA, origem
From
(
SELECT 'b' Origem,
   productid, 
   userid 
FROM buy
union all
SELECT 's' Origem,
   productid, 
   userid 
FROM sell
) tabelas
inner join users on users.userid=tabelas.userid
inner join products on products.productid=tabelas.productid
Where product.DATA LIKE '%x%'

Answer 3

您可以使用 EXISTS 子句：

SELECT userid, 
       USER.DATA, 
       productid, 
       product.DATA 
FROM   users, 
       products 
WHERE  ( EXISTS (SELECT * 
             FROM   buy 
                    INNER JOIN product 
                      ON ( buy.productid = product.productid ) 
             WHERE  buy.userid = users.userid 
                    AND product.DATA LIKE '%x%') ) 
        OR ( EXISTS (SELECT * 
                 FROM   sell 
                        INNER JOIN product 
                          ON ( sell.productid = product.productid ) 
                 WHERE  sell.userid = users.userid 
                        AND product.DATA LIKE '%x%') 

        AND products.userid = users.userid)