MySQL属性数据库 [英] MySQL attribute database

问题描述

我有一个属性数据库.每个属性值都存储在一个表中，该表具有其父属性的ID.

I have an attribute database. Each attribute value is stored in a table with an ID to its parent attribute.

在一个独立的表中，我将编写一条SQL语句来提取数据

In a stand alone table I would write an SQL statement that would pull data

WHERE username = '' AND domain = ''  

在属性表中，因为每个值都存储为单独的行，所以我不能这样做..我有一个联接，可以带回一个值+结果(请参见下文)，但是我需要基于如上所示的2条标准.

In the attribute table as each value is stored as a separate row, I can not do this.. I have a join that allows me to bring back one value + result (see below), however i need a result based on 2 criteria as shown above..

SELECT upa.value, up.status, u.status
  FROM user_product up, product_attribute pa, product p, user u, user_product_attribute upa

 WHERE pa.attribute_name = 'username'
   AND pa.product_attribute_id = upa.product_attribute_id
   AND pa.product_id = p.product_id
   AND u.user_id = up.user_id
   AND up.user_product_id = upa.user_product_id

   AND p.product_name = 'email'
   AND upa.value      = 'exampleuser'

我想我需要以某种结合的方式再次加入上述能力?任何输入都会有所帮助.

I presume i would need to join the above able again in some sort of union? Any input would be helpful..

谢谢

推荐答案

请不要使用隐式联接语法.需要第二组联接才能获得第二个属性.

Please don't use implicit join syntax. A second set of joins is needed to get a second attribute.

SELECT upa1.value, upa2.value, up1.status, u1.status 
  FROM product p
    /* These joins get attribute/value for 'username' attribute */
    INNER JOIN product_attribute pa1
      ON p.product_id = pa1.product_id
        AND pa1.attribute_name = 'username'
    INNER JOIN user_product_attribute upa1
      ON pa1.product_attribute_id = upa1.product_attribute_id
    INNER JOIN user_product up1
      ON upa1.user_product_id = up1.user_product_id
    INNER JOIN user u1
      ON up1.user_id = u1.user_id 
    /* These joins get attribute/value for 'domain' attribute */  
    INNER JOIN user_product_attribute upa2 
      ON upa1.user_product_id = upa2.user_product_id
    INNER JOIN product_attribute pa2
      ON upa2.product_attribute_id = pa2.product_attribute_id            
        AND pa2.attribute_name = 'domain'
  WHERE p.product_name = 'email'

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