获取上个月的记录

Question

我需要获取上个月的客户ID，数量和订单数量。

Paper::select('customer_id', DB::raw('SUM(price) as `sum`')
    ,DB::raw('COUNT(*) as `orders_per_month`'))
    ->where('created_at', '>=', Carbon::now()->startOfMonth())
    ->groupBy('customer_id')->get()

我尝试过，但是如果客户上个月没有订单，将不会选择它

Answer 1

尝试凉粉：

DB::raw('COALESCE(COUNT(*), 0) as `orders_per_month`')

此函数允许您定义默认值，否则为NULL。

http://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html#function_coalesce

更新：

我想，如果您只选择上个月订购的客户，那么绝对没有订单就不会吸引那些客户。您可以通过类似的方法实现所需的内容：

mysql> select * from cu;
+----+----------+
| id | name     |
+----+----------+
|  1 | Google   |
|  2 | Yahoo    |
|  3 | Mirosoft |
+----+----------+
3 rows in set (0.00 sec)

mysql> select * from so;
+----+-------------+---------------------+-------+
| id | customer_id | created_at          | price |
+----+-------------+---------------------+-------+
|  1 |           1 | 2016-08-23 12:12:12 |     2 |
|  2 |           1 | 2016-09-24 12:14:13 |     3 |
|  3 |           2 | 2016-09-25 00:00:00 |     5 |
|  4 |           2 | 2016-09-12 09:00:00 |     3 |
+----+-------------+---------------------+-------+
4 rows in set (0.00 sec)

mysql> select cu.id as customer_id, coalesce(sum(so.price),0) as total, coalesce(count(so.customer_id),0) as orders_per_month from cu left join so on (cu.id = so.customer_id) where so.created_at >= '2016-09-01 00:00:00' or so.created_at is null group by cu.id;
+-------------+-------+------------------+
| customer_id | total | orders_per_month |
+-------------+-------+------------------+
|           1 |     3 |                1 |
|           2 |     8 |                2 |
|           3 |     0 |                0 |
+-------------+-------+------------------+
3 rows in set (0.00 sec)

但是，结果查询不是一种高效的方法，您将不得不扫描所有客户并加入以获得没有订单的客户。分别获取有订单和无订单的客户列表并与UNION或通过您的应用程序代码合并，可能会更快。
mysql> select customer_id, sum(total) as total, sum(orders_per_month) as orders_per_month from (select id as customer_id, 0 as total, 0 as orders_per_month from cu union all select customer_id, sum(so.price) as total, count(so.customer_id) as orders_per_month from so where created_at >= '2016-09-01 00:00:00'group by customer_id) agg group by customer_id;
+-------------+-------+------------------+
| customer_id | total | orders_per_month |
+-------------+-------+------------------+
|           1 |     3 |                1 |
|           2 |     8 |                2 |
|           3 |     0 |                0 |
+-------------+-------+------------------+
3 rows in set (0.00 sec)

尝试一下
Paper::select('customer_id', DB::raw('SUM(price) as `sum`'),
             DB::raw('COUNT(*) as `orders_per_month`')
       )
     ->whereMonth('created_at', Carbon('first day of last month')->month)
     ->whereYear('created_at', Carbon('first day of last month')->year)
     ->groupBy('customer_id')->get()

Answer 2

尝试一下