在本篇文章中將給大家講解下CASE的其他用法講解：
使用帶有簡單CASE函數和CASE搜索函數的select語句在select語句中，CASE搜索函數允許根據比較值
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 |
+---------------+-----------+