在本篇文章中将给大家讲解下CASE的其他用法讲解：
使用带有简单CASE函数和CASE搜索函数的select语句在select语句中，CASE搜索函数允许根据比较值
select
CASE
WHEN good_type<2
THEN ‘<2‘
WHEN good_type>=2 AND good_type<3
THEN ‘>=2 && <3‘
ELSE ‘>=3‘ END AS good_now_type,
good_type,user_id,user_name
FROM t_main_order;
+---------------+-----------+---------+-----------+
| good_now_type | good_type | user_id | user_name |
+---------------+-----------+---------+-----------+
| <2 | 0 | 1 | tina |
| <2 | 0 | 2 | tige |
| <2 | 1 | 3 | five |
| >=2 && <3 | 2 | 4 | wate |
| >=3 | 3 | 5 | fiww |
| >=3 | 3 | 6 | www |
| >=3 | 3 | 7 | wfiw |
+---------------+-----------+---------+-----------+
CASE的其他用法
select
CASE
WHEN good_type<2
THEN ‘<2‘
WHEN good_type>=2 AND good_type<3
THEN ‘>=2 && <3‘ ELSE ‘>=3‘
END AS good_now_type,
count(*) AS num_count
FROM t_main_order
GROUP BY good_now_type
ORDER BY num_count;
+---------------+-----------+
| good_now_type | num_count |
+---------------+-----------+
| >=2 && <3 | 1 |
| <2 | 3 |
| >=3 | 3 |
+---------------+-----------+
原文地址：https://blog.51cto.com/14489558/2461079