mysql - 在一个查询中计算null和non-null字段

Question

输入表（名为ruchin）

id     comment           order_id          deleted_at
1        abc               1234              NULL
2        abcd              1234              TimeStamp
3        xyz               1234              NULL
4        pqr               1234              TimeStamp
5        as                4567               NULL
6        lo                4567               NULL

我希望输出为

order_id        count(deleted_at==Timestamp)    count(deleted_at==NULL)
1234                   2                                 2
4567                   0                                  2

我希望这是单一查询。我怎么能这样做？

Answer 1

您可以使用count()函数，因为它不会计算NULL值。

以下是查询：

SELECT order_id, 
       count(deleted_at) as 'del is not null',
       count(order_id) - count(deleted_at) as 'del is NULL' 
FROM ruchin 
GROUP BY order_id