我正在尝试将一些原始SQL迁移到我的模型上的Eloquent(或Query Builder)范围。我的零件历史表看起来像这样:
+----+---------+--------+------------+
| id | part_id | status | created_at |
+----+---------+--------+------------+
| 1 | 1 | 1 | ... |
| 2 | 1 | 2 | ... |
| 3 | 2 | 1 | ... |
| 4 | 1 | 2 | ... |
| 5 | 2 | 2 | ... |
| 6 | 1 | 3 | ... |
注意,同一part_id可能会有多个状态相同的条目。
目前我使用以下方法选择最新的状态:
$part = Part::leftjoin( DB::raw("
(SELECT t1.part_id, ph.status, t1.part_status_at
FROM (
SELECT part_id, max(created_at) part_status_at
FROM part_histories
GROUP BY part_id) t1
JOIN part_histories ph ON ph.part_id = t1.part_id AND t1.part_status_at = ph.created_at) as t2
)", 't2.part_id', '=', 'parts.id')->where( ... )
我正在尝试从这个模型中制作零件模型,到目前为止我有以下内容:
public function scopeWithLatestStatus($query)
{
return $query->join(DB::raw('part_histories ph'), function ($join) {
$join->on('ph.part_id', '=', 't1.id')->on('t1.part_status_at', '=', 'ph.created_at');
})
->from(DB::raw('(select part_id as id, max(created_at) part_status_at from part_histories GROUP BY part_id) t1'))
->select('t1.id', 'ph.part_status', 't1.part_status_at');
}
我已经做了一部分(但仍在使用一些原始的SQL),但我无法弄清剩下的部分。