how to add Check constraints on mysql that age calculate from Date of birth field and validate that age is greater than 18

Question

我已经使用mysql名称创建了具有六个属性id，name，lastname，dob（存储在Date数据类型中），性别，城市的人，并且我希望该值在dob（出生日期）中输入大于18 。我如何设置此约束，请帮忙

Answer 1

MySQL does not support check constraints. So, the only way to do this in MySQL is to create a trigger or wrap the insert in a stored procedure.

The specific logic that you would use is:

dob <= curdate() - interval 18 year

So, in almost any other database, this would look something like:

alter table t add constraint chk_t_dob check (dob <= curdate() - interval '18' year);

(Note: date operations vary among databases.)

Answer 2

Consider the following, on this the 24th June 2017...

CREATE TABLE dobs(dob DATE NOT NULL);

INSERT INTO dobs (dob)
SELECT '2012-01-01' x FROM (SELECT 1) a WHERE FLOOR(DATEDIFF(NOW(),'2012-01-01') / 365.24) >= 18;

INSERT INTO dobs (dob)
SELECT '1975-01-01' x FROM (SELECT 1) a WHERE FLOOR(DATEDIFF(NOW(),'1975-01-01') / 365.24) >= 18;

INSERT INTO dobs (dob)
SELECT '1999-06-25' x FROM (SELECT 1) a WHERE FLOOR(DATEDIFF(NOW(),'1999-06-25') / 365.24) >= 18;

INSERT INTO dobs (dob)
SELECT '1999-06-24' x FROM (SELECT 1) a WHERE FLOOR(DATEDIFF(NOW(),'1999-06-24') / 365.24) >= 18;

SELECT * FROM dobs;
+------------+
| dob        |
+------------+
| 1975-01-01 |
| 1999-06-24 |
+------------+