Question

我在创建查询时遇到问题，该查询应返回未分配给预算的成本中心。

数据库结构：

**Cost_center:**
+------+-----------+
|  id  |   title   |
+------+-----------+
| (PK) | (VARCHAR) |
+------+-----------+
\/
One 
to 
many
\/
**Budget_operation_scope_cost_center:**
+----------------+---------------------------+
| cost_center_id | budget_operation_scope_id |
+----------------+---------------------------+
| (FK)           | (FK)                      |
+----------------+---------------------------+
\/
Many 
to 
one
\/
**Budget_operation_scope:**
+------+-----------+-----------+
|  id  |   title   | budget_id |
+------+-----------+-----------+
| (PK) | (VARCHAR) | (FK)      |
+------+-----------+-----------+
\/
Many 
to 
one
\/
**Budget:**
+------+-------+
|  id  | year  |
+------+-------+
| (PK) | (INT) |
+------+-------+

管理以执行返回分配到预算成本中心列表的查询：

$query = $this->getEntityManager()
    ->createQueryBuilder()
    ->select('costCenter')
    ->from('ResourcesBundle:CostCenter', 'costCenter')
    ->leftJoin('costCenter.budgetOperationScope', 'budgetOperationScope')
    ->where('budgetOperationScope.budgetId = :budget')
    ->setParameter('budget', $budget)
    ->getQuery()->getResult();

问题：如何获取未分配给预算的成本中心？

Answer 1

此行过早地限制了您的查询，并有效地使您的左连接加入：

->where('budgetOperationScope.budgetId = :budget')

您可以将其移动到左连接中，如下所示：

->leftJoin('costCenter.budgetOperationScope', 'budgetOperationScope', 'WITH' 'budgetOperationScope.budgetId = :budget')

这样，当成本中心没有预算时，您将获得budgetOperationScope的空行。

所以你可以有效地做到：

->where('budgetOperationScope IS NULL')

所有在一起：

$query = $this->getEntityManager()
    ->createQueryBuilder()
    ->select('costCenter')
    ->from('ResourcesBundle:CostCenter', 'costCenter')
    ->leftJoin('costCenter.budgetOperationScope', 'budgetOperationScope', 'WITH' 'budgetOperationScope.budgetId = :budget')
    ->where('budgetOperationScope IS NULL')
    ->setParameter('budget', $budget)
    ->getQuery()->getResult();

多少学说左派加入

1 个答案: