如何在 MYSQL 中设置列​​的最大值？

Question

我有Table叫WORKERS，Table由totalNumberOfWorkers组成，我想设置worker的最大值为30，不能超过30，应该介于 0 到 30 之间。

我已经试过了，但它不起作用并显示错误，我的代码不正确。

ALTER TABLE WORKERS
CONSTRAINT WORKERS_CHECK CHECK (totalNumberOfWorkers => 0 AND totalNumberOfWorkers <31);

这里是 Table 所谓的 WORKERS

+------------------------+-------------+------+-----+---------+-------+
| Field                  | Type        | Null | Key | Default | Extra |
+------------------------+-------------+------+-----+---------+-------+
| WorkerID               | int(6)      | NO   | PRI | NULL    |       |
| dateOfWork             | date        | NO   |     | NULL    |       |
| timeOfWork             | time        | NO   |     | NULL    |       |
| descOfWorker           | varchar(50) | NO   |     | NULL    |       |
| totalNumberOfWorkers   | int(2)      | NO   |     | NULL    |       |
+------------------------+-------------+------+-----+---------+-------+

Answer 1

找到解决方案

ALTER TABLE WORKERS
ADD CONSTRAINT TOTALNUMBER_CHECK1 CHECK(totalNumberOfWorkers BETWEEN 1 AND 30);