JOIN DQL(symfony2)两个表之间的多个联接 [英] JOIN DQL (symfony2) multiple joins between two tables

问题描述

我的DQL查询有问题.我有一个表，其中包含3个外键userId，userRId和userAId.这些外键中的两个可能为NULL.

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.

我想在查询中联接所有外键，但是我不知道如何在同一张表之间联接两个或三个外键. (请参阅查询)有人可以给我一些想法吗?

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 ...

推荐答案

在DQL中，您对对象(实体)而不是表(基于映射)进行操作.因此，当您拥有这样的实体时:

In DQL you operate on objects(entities) not tables (based on mappings). So when you have entities like this:

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

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

您可以创建这样的查询(当您具有有效的映射时)

you can create query like this (when you have valid mappings)

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

但是，要配合使用，您需要映射信息.如果没有映射，则可以使用doctrine:mapping:import生成它，只需在symfony项目中键入以阅读更多php app/console help doctrine:mapping:import

But yeah to work with that you need mapping information. If you do not have mappings you can generate it using doctrine:mapping:import just type in you symfony project to read more php app/console help doctrine:mapping:import

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