Cakephp 3 按关联数据删除过滤

Question

在 CakePHP 3 中，假设我要删除所有 Departments 有一些名为“John”的 Employee（Departments 有很多 Employees，Employees 属于 Department)

最简单的方法是过滤所有这些部门，并在foreach循环中一个一个地删除它们：

$departments = $this->Departments->find()
    ->matching('Employees', function ($q) {
        return $q->where(['Employees.name' => 'John']);
    })
    ->all();

foreach ($departments as $department) {
    $this->Departments->delete($department);
}

这将为每条记录生成一个 SELECT 查询和一个 DELETE 查询。我希望只有一个查询由数据库发送和执行。像这样的：

DELETE Departments 
FROM departments Departments 
INNER JOIN employees Employees  ON 
    Employees.department_id = Departments.id 
    AND Employees.name = 'John';

阅读文档我发现了三种删除记录的方法：

• Using the Table object one by one，获取对象，然后删除。
• Using the Table with deleteAll，它采用目标表上的一组条件，而不是关联的条件。
• Using the ORM，同样只有一组条件。

有没有一种优雅的方式来使用 CakePHP 3 和 ORM 获取我的查询？

Answer 1

两件事：

第一：我建议的场景不正确

我的真实案例要复杂得多，所以我以众所周知的 employee-department 案例为例。我犯了一个错误：我需要删除属于某个部门的所有员工。我想从基于相关表的 con 条件的表中删除数据。

实际上，你不能删除有员工叫约翰的部门，因为部门不是空的，有约翰！ :D

类似这样的：

-- Create structures
CREATE TABLE IF NOT EXISTS departments (
  id int(11) NOT NULL AUTO_INCREMENT,
  name varchar(45) NOT NULL,
  PRIMARY KEY (id)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ;

CREATE TABLE IF NOT EXISTS employees (
  id int(11) NOT NULL AUTO_INCREMENT,
  department_id int(11) NOT NULL,
  name varchar(45) NOT NULL,
  PRIMARY KEY (id),
  KEY fk_employees_department_idx (department_id)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;

ALTER TABLE employees
  ADD CONSTRAINT fk_employees_departments FOREIGN KEY (department_id) REFERENCES departments (id) ON DELETE NO ACTION ON UPDATE NO ACTION;


-- Populate some data
INSERT INTO departments (id, name) VALUES
(1, 'Sales'),
(2, 'TI'),
(3, 'HHRR');

INSERT INTO employees (id, department_id, name) VALUES
(1, 1, 'John'),
(2, 1, 'Mary'),
(3, 2, 'Mark'),
(4, 3, 'Lorenzo');


-- Delete all employees that belong to the TI department (Mark should be removed)
DELETE emp FROM employees emp
INNER JOIN departments dep ON emp.department_id = dep.id AND dep.name = 'TI';

第二个：你可以在 CakePHP 中轻松做到这一点

你可以得到与上一个查询相同的结果：

    $departments = $this->Employees->Departments->find()
        ->select(['Departments.id'])
        ->where(['Departments.name' => 'TI']);
    $this->Employees->deleteAll(['Employees.department_id IN' => $departments]);

生成的 mysql 查询将是：

DELETE FROM employees WHERE department_id in 
(SELECT Departments.id AS `Departments__id` 
FROM departments Departments 
WHERE Departments.name = 'TI')

...这是正确的，而且易于理解。 @arilia，您的第一个答案指向了这个方向。很抱歉造成混乱。

Answer 2

deleteAll 只是一个环绕

$this->Departments->query()
   ->delete()
   ->where([...])
   ->execute();

所以我认为，以类似的方式，可以这样做：

$departments = $this->Departments->query()
    ->delete()
    ->matching('Employees', function ($q) {
        return $q->where(['Employees.name' => 'John']);
    })
    ->execute();

但在这种情况下，您会注意到匹配条件被忽略了。我看到有一个开放的ticket 关于那个

如果您只想使用两个查询，您可以在第二个查询中执行一个查询来检索所有 id 并删除所有：

$departments_ids = $this->Departments->find()
    ->select(['id'])
    ->matching('Employees', function ($q) {
        return $q->where(['Employees.name' => 'John']);
    })
    ->toArray();

$this->Departments->deleteAll(['id' => $departments_ids ]);

结果如下：

DELETE FROM departments WHERE id IN
(
    // id list here
)

另一种解决方案是在子查询中转换您的内部联接。实际上，您想删除几乎拥有名为 John 的 Employee 的所有部门。

$employees = $this->Departments->Employees->find()
    ->select(['department_id'])
    ->distinct()
    ->where(['Employees.name' => 'John']);

$departments = $this->Departments->query()
    ->delete()
    ->where(['id IN' => $employees])
    ->execute();