join - JOIN DQL (symfony2) multiple joins between two tables

Question

I have a problem in my DQL query. I have a table which has 3 foreign keys userId, userRId and userAId. Two of those foreign keys may be NULL.

I want to join all the foreign keys in the query but i don't know how to join two or three foreign keys between the same tables. (see query ) Could somebody give me some ideas??

   **TABLE A**
   id    userId   userRId   userAId
   1     2        NULL      NULL
   1     2         1        NULL
   1     2        NULL         1

**TABLE USER**
userId  name
  2     xxxx
  1     xxxx

The DQL query:

"SELECT FROM nasyBundle:A a JOIN a.userId u , a JOIN userRId , a JOIN userAid
         WHERE ...

Answer 1

在 DQL 中，您对对象（实体）而不是表（基于映射）进行操作。所以当你有这样的实体时：

class User
{
    private $id;
    private $name;
}

class TableA
{
    private $id;
    private $user;
    private $userR;
    private $userA;
}

您可以像这样创建查询（当您有有效的映射时）

SELECT a
FROM nastyBundle:TableA a
INNER JOIN a.user u
LEFT JOIN a.userR ur
LEFT JOIN a.userA ua

但是，是的，要使用它，您需要映射信息。如果您没有映射，您可以使用学说生成它：映射：导入只需输入您的 symfony 项目以阅读更多信息php app/console help doctrine:mapping:import