Why AUTO_INCREMENT does not work?

Question

ALTER TABLE Employees
AUTO_INCREMENT=8
INSERT INTO Employees(firstname,lastname,salary)
VALUES
('Greta','Wu',1200)
SELECT *
FROM Employees
ORDER BY id DESC

Answer 1

You have 3 different statements in your description (ALTER TABLE, INSERT, SELECT).
Each statement should end with a ; semicolon.

Answer 2

Ok, i remove the alter table and the auto-increment and everything goes fine. I don't even know why.

Answer 3

Does the SQL engine report an error? If so, what is the error message?

Answer 4

It says that the AUTO-INCREMENT should be replaced with "SERIAL" in PostgreSQL or "IDENTITY" in SQL SERVER. This is what says.