Laravel 和 MySQL 在连接上有连接？

Question

我需要在已连接的表上连接一个表，因为我需要的另一个表中的数据也分布在另一个表中。到目前为止，这是我的 SQL 模型：

现在我还需要加入地址表和加入的子表，因为我还需要每个孩子的地址。我唯一的问题是，如何根据 childs.address_id 加入表地址？

我已经尝试过了：

INNER JOIN `addresses` AS `addresse_child` ON `childs`.`address_id` = `addresses`.`id`

很遗憾没有工作..

到目前为止我的 SQL 查询 (DB::getQueryLog())

SELECT `assignments`.`id` AS `assignment_id`,
       `assignments`.`persons` AS `assignment_persons`,
       `assignments`.`start_date` AS `assignment_start_date`,
       `assignments`.`end_date` AS `assignment_end_date`,
       `addresses`.`id` AS `address_id`,
       `addresses`.`first_name` AS `address_first_name`,
       `addresses`.`last_name` AS `address_last_name`,
       `addresses`.`company` AS `address_company`,
       `childs`.`id` AS `child_id`,
       `childs`.`address_id` AS `child_address_id`,
       `childs`.`sibling_id` AS `child_sibling_id`,
       `childs`.`height` AS `child_height`,
       `childs`.`weight` AS `child_weight`
FROM `assignments`
INNER JOIN `addresses` ON `assignments`.`address_id` = `addresses`.`id`
INNER JOIN `childs` ON `assignments`.`id` = `childs`.`assignment_id`
WHERE `assignments`.`deleted_at` IS NULL
  AND `addresses`.`deleted_at` IS NULL
  AND `childs`.`deleted_at` IS NULL

我的 Laravel SQL 命令：

$assignment_data =  DB::table('assignments')
            ->join('addresses', 'assignments.address_id',  '=', 'addresses.id')
            ->join('childs', 'assignments.id',  '=', 'childs.assignment_id')
            ->select(
                'assignments.id as assignment_id',
                'assignments.persons as assignment_persons',
                'assignments.start_date as assignment_start_date',
                'assignments.end_date as assignment_end_date',
                'addresses.id as address_id',
                'addresses.first_name as address_first_name',
                'addresses.last_name as address_last_name',
                'addresses.company as address_company',
                'childs.id as child_id',
                'childs.address_id as child_address_id',
                'childs.sibling_id as child_sibling_id',
                'childs.height as child_height',
                'childs.weight as child_weight'

            )
            ->whereNull('assignments.deleted_at')
            ->whereNull('addresses.deleted_at')
            ->whereNull('childs.deleted_at')
            ->get();

Answer 1

你应该能够做到；

SELECT `assignments`.`id` AS `assignment_id`,
       `assignments`.`persons` AS `assignment_persons`,
       `assignments`.`start_date` AS `assignment_start_date`,
       `assignments`.`end_date` AS `assignment_end_date`,
       `addresses`.`id` AS `address_id`,
       `addresses`.`first_name` AS `address_first_name`,
       `addresses`.`last_name` AS `address_last_name`,
       `addresses`.`company` AS `address_company`,
       `childs`.`id` AS `child_id`,
       `childs`.`address_id` AS `child_address_id`,
       `childs`.`sibling_id` AS `child_sibling_id`,
       `childs`.`height` AS `child_height`,
       `childs`.`weight` AS `child_weight`
FROM `assignments`
INNER JOIN `addresses` ON `assignments`.`address_id` = `addresses`.`id`
INNER JOIN `childs` ON `assignments`.`id` = `childs`.`assignment_id` AND 
                       `childs`.`address_id` = `addresses`.`id`
WHERE `assignments`.`deleted_at` IS NULL
  AND `addresses`.`deleted_at` IS NULL
  AND `childs`.`deleted_at` IS NULL

而在 Laravel 中，这可以通过做来实现；

 $assignment_data =  DB::table('assignments')
        ->join('addresses', 'assignments.address_id',  '=', 'addresses.id')
        ->join('childs', function($q) { 
               $q->on('assignments.id',  '=', 'childs.assignment_id')
                 ->where('childs.address_id', '=', 'addresses.id');
          })
        ->select(
            'assignments.id as assignment_id',
            'assignments.persons as assignment_persons',
            'assignments.start_date as assignment_start_date',
            'assignments.end_date as assignment_end_date',
            'addresses.id as address_id',
            'addresses.first_name as address_first_name',
            'addresses.last_name as address_last_name',
            'addresses.company as address_company',
            'childs.id as child_id',
            'childs.address_id as child_address_id',
            'childs.sibling_id as child_sibling_id',
            'childs.height as child_height',
            'childs.weight as child_weight'

        )
        ->whereNull('assignments.deleted_at')
        ->whereNull('addresses.deleted_at')
        ->whereNull('childs.deleted_at')
        ->get();

但是您应该注意，通过执行 INNER JOINS，您只会在每个表中有行的情况下获得结果。您最好还是使用 LEFT JOINS，这取决于您的数据是如何被需要的。