Mysql select where t4.name=x and t2 or t3 have a t1.user !? :)

To explain my problem lets imagine 4 tables.

users - (userid, user.data)

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

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

product - (productid, product.data)

I want to do a select that returns all the users and product data when there is a user that have products with X on the name to buy or sell.

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 开发者_JS百科product.DATA LIKE '%x%'  

this doesnt work but I belive you get the idea of what I am tryng to do.

---

Try a union like below:

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%'  

---

Thanks a lot guys!

With the help from a friend end up making something like this:

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%'

---

You could use the EXISTS clause:

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)