MySQL在给定范围内按步长查询数据

所以基本上我有一个用户表，它有一个名为“completed_surveys”的列，它保存了完成的调查的总数

我需要创建一个查询，该查询将采用步长编号，并按该范围对它们进行分组

符合我需要的示例结果：

+---------+-------------------+
|  range  | completed_surveys |
+---------+-------------------+
| 0-14    |              4566 |
| 14-28   |              3412 |
| 28-42   |              5456 |
| 42-56   |                33 |
| 56-70   |                31 |
| 70-84   |               441 |
| 84-98   |               576 |
| 98-112  |                23 |
| 112-126 |                12 |
| 126-140 |                 1 |
+---------+-------------------+

select concat(what should i add here??) as `range`,
       count(users.completed_surveys) as `completed_surveys` from users WHERE users.completed_surveys > 0 group by 1 order by users.completed_surveys;

到目前为止我拥有的：

+---------+-------------------+
|  range  | completed_surveys |
+---------+-------------------+
| 0-14    |              4566 |
| 14-28   |              3412 |
| 28-42   |              5456 |
| 42-56   |                33 |
| 56-70   |                31 |
| 70-84   |               441 |
| 84-98   |               576 |
| 98-112  |                23 |
| 112-126 |                12 |
| 126-140 |                 1 |
+---------+-------------------+

select concat(what should i add here??) as `range`,
       count(users.completed_surveys) as `completed_surveys` from users WHERE users.completed_surveys > 0 group by 1 order by users.completed_surveys;

---

我认为这个查询是正确的，但是在concat函数中，我真的不知道如何将前面的数字增加14。有什么想法吗？

一个想法是首先创建一个值为0..9的帮助表

CREATE TABLE tmp ( i int );
INSERT INTO tmp VALUES (0) , (1) ... (9);

然后连接两个表：

SELECT concat(i,' - ',(i+1)*7) as `range`,
  count(users.completed_surveys) as `completed_surveys` from users
INNER JOIN tmp ON (users.completed_surveys>tmp.i AND users.completed_surveys<=(i+1)*7)
WHERE users.completed_surveys > 0 
GROUP BY tmp.i
ORDER BY tmp.i

选择concat（i'，-'，（i+1）*7）作为“范围”，
将（用户.已完成的调查）统计为来自用户的“已完成的调查”
内部加入tmp ON（users.completed_surveys>tmp.i和users.completed_surveys 0
tmp.i分组
tmp.i订购

请参见