如何左连接然后使用 where 日期获取第二个表中的最新行 [关闭]

Question

有人知道如何查询这个示例表吗？

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我认为这是从表 branches 到表 branch_operationals 的左连接，我应该将 where date 放入查询中。

以下是示例：

表格branches

id	code	name
1	T2QD5	NewYork_Spot
2	MKGHB	London_Spot
3	IGHCZ	Miami_Spot
4	PJDSO	Tokyo_Spot

表格branch_operationals

id	branch_id	date	status
1	2	2020-12-05	closed
2	2	2020-12-06	closed
3	3	2020-12-06	open
4	2	2020-12-06	closed
5	2	2020-12-06	open
6	1	2020-12-16	closed

预期结果

id (from 'branches.id')	code	name	date	status
1	T2QD5	NewYork_Spot	2020-12-09	closed
2	MKGHB	London_Spot	2020-12-09	open
3	IGHCZ	Miami_Spot	2020-12-09	open
4	PJDSO	Tokyo_Spot	2020-12-09	null

这是我当前的查询：

select * from `branches` left join `branch_operationals` on `branches`.`id` = `branch_operationals`.`branch_id` where (`date` = 2020-12-21)

但是，它返回 null（空数据）。但是当我删除where 语句时，它会显示表branch_operationals 中的所有数据以及表branches 中的每个数据。

目前我使用的是 Laravel 8，这是我的 Laravel 语法：

$branches = Branch::leftJoin('branch_operationals','branches.id','branch_operationals.branch_id')->where(function($q) use($request){
    if($request->search){
        $q->where(function($q) use($request){
            $q->where('code','like','%'.$request->search.'%');
            $q->orWhere('name','like','%'.$request->search.'%');
        });
    }

    if($request->date_filter){
            $q->where('date',$request->date_filter);
    }else{
            $q->where('date',\Carbon\Carbon::now()->toDateString());
    }
})->get();

我需要查询语法或 Laravel Eloquent 语法。

谁能帮帮我？感谢您的关注:)

Answer 1

也许对你有用

select b.id ,b.code,b.name ,'2020-12-06' date ,o.status from branch b 
left join  ( select  bo.id, bo.branch_id, bo.date, bo.status from
  (select branch_id , max(id) id  from branch_operationals where date='2020-12-06' group by branch_id ) as tmp
  join branch_operationals bo on bo.id=tmp.id ) as o on b.id=o.branch_id

Answer 2

我可以为您提供正常的查询语法LEFT JOIN。

您的查询的问题是您正在通过在WHERE 子句中的左联接表上应用条件来执行INNER JOIN。您可以通过以下方式达到预期的效果：

select * from
(select b.*, bo.*,  -- use the needed column names with proper alias here. I have used *
        row_number() over (partition by b.id order by bo.date desc) as rn
  from branches b 
  left join branch_operationals bo on b.id = bo.branch_id and date <= 2020-12-21) t 
where rn = 1