[英]Laravel/Eloquent: replace with() for leftjoin() or join()
眾所周知,這對於mysql來說是一個不好的選擇
$authors = Authors::all();
foreach ($authors as $author) {
echo $author->name;
foreach ($author->posts as $post) {
echo $post->title;
}
}
如果我們有3位作者,每位作者3條帖子,那么雄辯地進行4條SQL查詢(1位作者,每位作者1位)
$authors = Authors::with('posts')
->all();
foreach ($authors as $author) {
echo $author->name;
foreach ($author->posts as $post) {
echo $post->title;
}
}
這對於mysql更好,因為現在我們只有2個SQL查詢器(1個用於作者,1個用於帖子)。
查詢就像:
select * from `authors` where `authors`.`deleted_at` is null
select * from `posts`
where `posts`.`deleted_at` is null and `author`.`id` in (?, ?, ?)
但是,是否可以維護最后的PHP代碼,但進行這樣的SQL查詢呢?
select authors.*, posts.* from `authors`
left join posts on posts.author_id = authors.id
where `authors`.`deleted_at` is null
您可以嘗試本地范圍。 代碼不會完全像那樣,但是可能會像這樣結束:
$authors = Authors::theNameYouChooseForTheScope()->get();
您將定義如下范圍:
public function scopeTheNameYouChooseForTheScope($query)
{
return $query->leftJoin('posts', 'authors.id', '=', 'posts.author_id')
}
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