MySQL5.7.29能正常排序,是不是一下效果，最好把表结构也发出来。

CREATE TABLE `milk_tea` (
  `id` int(11) NOT NULL,
  `in_price` decimal(10,1) DEFAULT NULL,
  `sale_price` decimal(10,1) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

INSERT INTO `milk_tea` VALUES (1,15.5,NULL),(2,2.1,2.5),(3,10.8,15.0),(4,9.3,15.0),(5,8.8,15.0),(6,12.3,20.0);

mysql> select id,in_price,sale_price ,IFNULL(sale_price,10) 
from milk_tea; 
+----+----------+------------+-----------------------+
| id | in_price | sale_price | IFNULL(sale_price,10) |
+----+----------+------------+-----------------------+
|  1 |     15.5 |       NULL |                  10.0 |
|  2 |      2.1 |        2.5 |                   2.5 |
|  3 |     10.8 |       15.0 |                  15.0 |
|  4 |      9.3 |       15.0 |                  15.0 |
|  5 |      8.8 |       15.0 |                  15.0 |
|  6 |     12.3 |       20.0 |                  20.0 |
+----+----------+------------+-----------------------+
6 rows in set (0.00 sec)

mysql> select id,in_price,sale_price ,IFNULL(sale_price,10) 
from milk_tea  
order by IFNULL(sale_price,10)  ;
+----+----------+------------+-----------------------+
| id | in_price | sale_price | IFNULL(sale_price,10) |
+----+----------+------------+-----------------------+
|  2 |      2.1 |        2.5 |                   2.5 |
|  1 |     15.5 |       NULL |                  10.0 |
|  3 |     10.8 |       15.0 |                  15.0 |
|  4 |      9.3 |       15.0 |                  15.0 |
|  5 |      8.8 |       15.0 |                  15.0 |
|  6 |     12.3 |       20.0 |                  20.0 |
+----+----------+------------+-----------------------+

你好，这就是我排序用的表。

1.需要表结构create 创建命令。
show create table table_name;
2.数据库版本。
select version();
3.还有答复的那样的效果吗？

学习了