mysql - MacOS MySQL_8的where子句中TINYINT UNSIGNED数据列不能减

Question

以下是使用 MacOS 运行的 MySQL(8.0.x) 中的数据：

ysql> desc t_room;
+--------------+-------------------+------+-----+---------+-------+
| Field        | Type              | Null | Key | Default | Extra |
+--------------+-------------------+------+-----+---------+-------+
| roomNum      | varchar(60)       | NO   | PRI | NULL    |       |
| roomType     | varchar(20)       | NO   |     | NULL    |       |
| roomDesc     | varchar(400)      | YES  |     | NULL    |       |
| rentPayDay   | tinyint unsigned  | YES  |     | NULL    |       |
| rentFee      | smallint unsigned | NO   |     | NULL    |       |
| asstMine     | varchar(400)      | YES  |     | NULL    |       |
| asstOwner    | varchar(400)      | YES  |     | NULL    |       |
| owner        | varchar(30)       | YES  |     | NULL    |       |
| signDate     | date              | YES  |     | NULL    |       |
| contract     | mediumblob        | YES  |     | NULL    |       |
| roomFacility | varchar(120)      | YES  |     | NULL    |       |
+--------------+-------------------+------+-----+---------+-------+
11 rows in set (0.00 sec)

mysql> select rentPayDay from t_room;
+------------+
| rentPayDay |
+------------+
|         15 |
|         20 |
|         25 |
|         10 |
+------------+
4 rows in set (0.00 sec)

当我使用下面的 where 子句进行查询时，一切都很好：

mysql> select roomNum, owner, rentPayDay from t_room where rentPayDay - 10 <= 5;
+---------------+--------+------------+
| roomNum       | owner  | rentPayDay |
+---------------+--------+------------+
| xxxC-906     | John   |         15 |
| xxxxx-908    | Doe   |         10 |
+---------------+--------+------------+
2 rows in set (0.00 sec)

但是，当我减去一个可能大于某些rentPayDay 值的值时，如下所示：

mysql> select roomNum, owner, rentPayDay from t_room where rentPayDay - 11 <= 5;

事情出错了：

ERROR 1690 (22003): BIGINT UNSIGNED value is out of range in '(`dev_learn`.`t_room`.`rentPayDay` - 11)'

有人对此有任何想法吗？为什么 TINYINT 数据不能在 where 子句中减去更大的数值？

Answer 1

AnUNSIGNED TINYINT的范围为 0-255，其中不能表示负值。

如果您遇到投射错误，请考虑：

SELECT * FROM rooms WHERE CAST(rentPayDay AS DECIMAL) - 11 <= 5;

如此处所示。

Answer 2

参考@Akina 和@Ken White，这是我对这个错误的猜测：

the express {columnName OPERATOR -value-} still be restricted as a whole with the same definition of {columnName}.

我不知道 MySQL 对我的查询的响应中发生了什么以及发生了什么。解决这个问题的更好方法：

please refer to @Akina comment under my original question post.

非常感谢所有关心和帮助的人。