Chave primária múltipla colums
ALTER TABLE Student
ADD CONSTRAINT PK_Student PRIMARY KEY (Rollno,LastName);
sree_007
ALTER TABLE Student
ADD CONSTRAINT PK_Student PRIMARY KEY (Rollno,LastName);
CREATE TABLE Colleges (
college_id INT,
college_code VARCHAR(20),
college_name VARCHAR(50),
CONSTRAINT CollegePK PRIMARY KEY (college_id, college_code)
);