php - Propel 在使用别名连接表时添加 CROSS JOIN 查询

Question

尝试在 Propel 2 中做一个相当简单的查询。我有一个 Person 表和一个 Possession 表——一个人可以拥有很多属性(property)，但每种属性(property)类型只能有一个。所以一个人可以拥有 1 本书、1 辆车等。我正在尝试在 Propel 中编写一个查询，如果他们有车，它将返回所有人及其车名。这是代码和生成的查询:

$x = PersonQuery::create()
  ->groupById()
  ->leftJoinPossession()
  ->addJoinCondition('Possession','Possession.possession_type = ?', 'car')
  ->withColumn('Possession.possession_name', 'CarName')
  ->where('Possession.possession_name IS NOT NULL')
  ->find()
  ->toString();

//resulting sql
SELECT person.id, possession.possession_name as CarName
FROM person
LEFT JOIN possession  ON (person.id=possession.person_id AND possession.possession_type = 'car')
WHERE possession.possession_name IS NOT NULL;

这按预期工作。但是，我需要对 possession 表进行多次连接(例如，为每个人获取书籍)，因此我需要使用别名。下面是当我修改前面的查询只是为了使用属性(property)表的别名(并且还为每个人获取书)时发生的情况:

$x = PersonQuery::create()
  ->groupById()
  ->leftJoinPossession('p')
  ->addJoinCondition('p','p.possession_type = ?', 'car')
  ->leftJoinPossession('p2') 
  ->addJoinCondition('p2','p2.possession_type = ?', 'book')
  ->withColumn('p.possession_name', 'CarName')
  ->withColumn('p2.possession_name', 'BookName')
  ->where('p.possession_name IS NOT NULL')
  ->find()
  ->toString();

//resulting sql
SELECT person.id, p.possession_name as CarName, p2.possession_name as BookName
FROM person
CROSS JOIN possession
LEFT JOIN possession p ON (person.id=p.person_id AND p.possession_type = 'car')
LEFT JOIN possession p2 ON (person.id=p2.person_id AND p2.possession_type = 'book')
WHERE p.possession_name IS NOT NULL;

如您所见，出于某种原因，Propel 在查询中添加了“CROSS JOIN possession”。这不会改变查询的结果，但会使其非常慢。关于如何告诉 Propel 不要使用 CROSS JOIN 同时仍然为我的联接表使用别名的任何想法？ (如果我去掉 'where' 子句，CROSS JOIN 也会消失)

Answer 1

找到了解决此问题的方法。问题是，当我尝试对同一个表进行多个左连接(通过使用别名)时，Propel 也会包含对该表的交叉连接。但是，我发现如果第一个连接没有使用别名，Propel 不会添加交叉连接。

所以，总而言之，这是行不通的:

$x = PersonQuery::create()
  ->groupById()
  ->leftJoinPossession('p')
  ->addJoinCondition('p','p.possession_type = ?', 'car')
  ->leftJoinPossession('p2') 
  ->addJoinCondition('p2','p2.possession_type = ?', 'book')
  ->withColumn('p.possession_name', 'CarName')
  ->withColumn('p2.possession_name', 'BookName')
  ->where('p.possession_name IS NOT NULL')
  ->find()
  ->toString();

//resulting sql
SELECT person.id, p.possession_name as CarName, p2.possession_name as BookName
FROM person
CROSS JOIN possession
LEFT JOIN possession p ON (person.id=p.person_id AND p.possession_type = 'car')
LEFT JOIN possession p2 ON (person.id=p2.person_id AND p2.possession_type = 'book')
WHERE p.possession_name IS NOT NULL;

但这按预期工作:

$x = PersonQuery::create()
  ->groupById()
  ->leftJoinPossession() //changed
  ->addJoinCondition('Possession','Possession.possession_type = ?', 'car') //changed
  ->leftJoinPossession('p2') 
  ->addJoinCondition('p2','p2.possession_type = ?', 'book')
  ->withColumn('p.possession_name', 'CarName')
  ->withColumn('p2.possession_name', 'BookName')
  ->where('p.possession_name IS NOT NULL')
  ->find()
  ->toString();

//resulting sql
SELECT person.id, p.possession_name as CarName, p2.possession_name as BookName
FROM person
LEFT JOIN possession ON (person.id=posession.person_id AND posession.possession_type = 'car')
LEFT JOIN possession p2 ON (person.id=p2.person_id AND p2.possession_type = 'book')
WHERE p.possession_name IS NOT NULL;