在一行中输出多个计数的一个表记录

问题描述

这是一个示例表CALLRECORD：

    +--------+------------+
    |callid  |   rating   |
    |1       |            |
    |2       |   5        |
    |3       |            |
    |4       |   1        |
    |5       |            |
    +--------+------------+

输出呼叫总数，已评级呼叫数，平均评级和未评级呼叫数没有问题：

select count(*) as total from callrecord;
select count(*) as rated,avg(rating) as average_rating from callrecord where rating is not null;
select count(*) as unrated from callrecord where rating is null;

    +--------+
    |total   |
    |5       |
    +--------+

    +--------+------------+
    |rated   |average     |
    |2       |3           |
    +--------+------------+

    +--------+
    |unrated |
    |3       |
    +--------+

我正在寻找如何通过单个sql请求将以上所有内容输出到一行：

    +--------+--------+------------+---------+
    |total   |rated   |average     |unrated  |
    |5       |2       |3           |3        |
    +--------+--------+------------+---------|

db 提琴here

解决方法

大多数聚合函数都会忽略null值，因此您想要的更简单，您可能会认为：

select 
    count(*) total,-- total number of rows
    count(rating) as rated,-- count of non-null ratings
    avg(rating) average,-- avg ignore `null`
    count(*) - count(rating) unrated -- count of null ratings
from mytable

,

尝试在SUM聚合中使用CASE语句。下面的示例。

{
  "api_key": "YOUR_API_KEY","@type": "searchPublicChat","username": "@username"
}