mysql - 按列值的 LIKE 分组

Question

给定这样一个假设的查询:

SELECT COUNT(*)
FROM subscriptions
GROUP by plan_type

还有一个类似于下表的表格:

+----+-----------------------+-------------+--+
| id |       plan_type       | customer_id |  |
+----+-----------------------+-------------+--+
|  1 | gold_2017             |         523 |  |
|  2 | gold_2016_recurring   |        2300 |  |
|  3 | silver_2016           |         234 |  |
|  4 | silver_2017_recurring |        2593 |  |
|  5 | platinum_recurring    |        4123 |  |
+----+-----------------------+-------------+--+

期望的结果:

+-------+----------+
| count |   type   |
+-------+----------+
|     2 | gold     |
|     2 | silver   |
|     1 | platinum |
+-------+----------+

有没有什么方法可以使用 GROUP BY 和 LIKE 语句(LIKE “silver”、LIKE “gold”、LIKE “platinum”等)对这些条目进行分组？

Answer 1

你可以使用case:

SELECT (CASE WHEN plan_type LIKE 'silver%' THEN 'silver'
             WHEN plan_type LIKE 'gold%' THEN 'gold'
             WHEN plan_type LIKE 'platinum%' THEN 'platinum'
        END) as plan_grp, COUNT(*)
FROM subscriptions
GROUP by (CASE WHEN plan_type LIKE 'silver%' THEN 'silver'
               WHEN plan_type LIKE 'gold%' THEN 'gold'
               WHEN plan_type LIKE 'platinum%' THEN 'platinum'
          END);

一些数据库允许您在 GROUP BY 中使用列别名。