공식문서

ALTER TABLE

https://dev.mysql.com/doc/refman/8.0/en/alter-table.html

ALTER TABLE 예시

https://dev.mysql.com/doc/refman/8.0/en/alter-table-examples.html

SQL DEFAULT Constraint

이 w3schools가 쉽게 잘 나와있다.
https://www.w3schools.com/sql/sql_default.asp

추가

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    City varchar(255) DEFAULT 'Sandnes'
);

CREATE TABLE Orders (
    ID int NOT NULL,
    OrderNumber int NOT NULL,
    OrderDate date DEFAULT GETDATE()
);

수정

ALTER TABLE Persons
ALTER City SET DEFAULT 'Sandnes';

삭제

ALTER TABLE Persons
ALTER City DROP DEFAULT;