MySQL Constraints

 List of Constraints:

Data Table without constraints:

Syntax:

Code:

CREATE TABLE student( id INT NOT NULL UNIQUE, name VARCHAR(50) NOT NULL, age INT NOT NULL CHECK(age >= 18), gender VARCHAR(1) NOT NULL, phone VARCHAR(10) NOT NULL UNIQUE, city VARCHAR(15) NOT NULL DEFAULT 'Mul' );

Test NOT NULL by skip gender column value

INSERT INTO student(id,name,age,gender,phone,city)
VALUES
(2,"Aqib","18","4015155","mul");

SQL

Test DEFAULT value by skip city column value

INSERT INTO student(id,name,age,gender,phone,city)
VALUES
(3,"Salman Khan","20","M","4012155");

SQL

Test UNIQUE value by add same phone number

INSERT INTO student(id,name,age,gender,phone,city)
VALUES
(4,"Saqib","21","F","4016155");

SQL

Test constraints on AGE 

INSERT INTO student(id,name,age,gender,phone,city)
VALUES
(5,"Asif","18","F","4017755");