原则 2:如何使用子查询列(在 SELECT 子句中) [英] Doctrine 2: how do you use a subquery column (in the SELECT clause)

问题描述

我正在尝试使用 SELECT 子句中的子查询执行简单的选择查询，但根本没有找到执行此操作的方法.我已经尝试过 DQL 和 QueryBuilder，但都不起作用.代码如下，请不要说我只能使用连接，这是一个简单的例子，只是为了说明问题，我有子查询的合法用例.

I'm trying to do a simple select query with a subquery in the SELECT clause and have simply not found a way to do it. I've tried with both DQL and with the QueryBuilder, neither work. The code follows, please don't say I could just use a join, this is a simplified example just to illustrate the problem, I have legitimate use cases for subqueries.

// With QueryBuilder
$query = $qb->select(array('a', 
                           '(SELECT at.addresstypeName 
                               FROM e:Addresstype at 
                              WHERE at.addresstypeId = a.addresstypeId
                            ) AS addresstypeName'))
            ->from('e:Address', 'a')
            ->where('a.addressId = :addressId')
            ->setParameter('addressId', 1);

// With DQL
$dql = "SELECT a, 
               (SELECT at.addresstypeName 
                  FROM e:Addresstype at 
                 WHERE at.addresstypeId = a.addresstypeId
               ) AS addresstypeName 
          FROM e:Address a 
         WHERE a.addressId = :addressId";
$query = $em->createQuery($dql)->setParameter(':addressId', 1);

在地址表上定义了以下关系:

The following relationship is defined on the Address table:

/**
 * @ORMManyToOne(targetEntity="Addresstype")
 * @ORMJoinColumns({
 *   @ORMJoinColumn(name="addresstype_id", referencedColumnName="addresstype_id")
 * })
 */
protected $addresstype;

在原生 SQL 中，查询如下所示:

In native SQL, the query would look like this:

SELECT
    a.*,
    (
        SELECT at.addresstype_name
        FROM addresstype at
        WHERE at.addresstype_id = a.addresstype_id
    ) AS addresstype_name
FROM address a
WHERE a.address_id = 1

有什么想法吗?

推荐答案

$query = $qb->select('a')
    ->addSelect('(SELECT at.addresstypeName
            FROM e:Addresstype at
            WHERE at.addresstypeId = a.addresstypeId) AS addresstypeName'
        )
    ->from('e:Address', 'a')
    ->where('a.addressId = :addressId')
    ->setParameter('addressId', 1);

这篇关于原则 2:如何使用子查询列(在 SELECT 子句中)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！