W3Schools SQL | #46 SQL PRIMARY KEY CONSTRAINT 이용법

SQL PRIMARY KEY Constraint

SQL PRIMARY KEY Constraint

레코드를 식별하는 역할을 하는 column을 정하는 명령어

SQL PRIMARY KEY on CREATE TABLE

CREATE TABLE Persons (
    ID int NOT NULL PRIMARY KEY, 
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int
);

SQL PRIMARY KEY on ALTER TABLE

ALTER TABLE Persons
ADD PRIMARY KEY (ID);

DROP a PRIMARY KEY Constraint

ALTER TABLE Persons
DROP PRIMARY KEY;