How to create a statement in MySQL?

Question

MySQL

There are 4 fields in the table: id, workday, dayoff, sumdays
I want to add a check that the sum of workday + dayoff recorded in sumdays is no more than 365. I wrote:

CREATE ASSERTION Limitdays CHECK (
    NOT EXISTS (
        SELECT `workday`, `dayoff`, `sumdays`
        FROM `worker`
        WHERE id=id
        AND `sumdays` < 367
    )
);

Swears at the error
right syntax to use near 'ASSERTION Limitdays CHECK (
NOT EXISTS (
SELECT `workday`, `dayoff' at line 1
) Google almost nothing sensible at all. There are inter-table statements, but I have everything inside one table .. .

Answer 1

MySQL does not support ASSERT.
Use BEFORE INSERT and BEFORE UPDATE triggers.