SQL NOT NULL Constraint

The NOT NULL constraint allows a column not to accept NULL values. This specify that NOT NULL Constraint enforce the field to accept a value. Simply, neither you insert or update a new record without  adding a value to this field.

Understand with Example

The Tutorial illustrates an example from 'SQL NOT NULL Constraint'. In this example, we create a table Stu_Class_10 with the help of create statement. When you create a table ,we define a field attribute, data type, null value etc. The following SQL enforces the Columns "Stu_Id","Stu_Name" and "Stu_Class" column not to accept NULL values. The insert into adds the records value into table'Stu_Class_10'.The select statement show you the records from table 'Stu_Class_10'.When you do not insert any value to record ,the records shows you SQL NOT NULL Constraint.

Create Table Stu_Class_10

CREATE TABLE Stu_Class_10(
Stu_Id integer(2) NOT NULL, 
Stu_Name varchar(15) NOT NULL, 
Stu_Class  varchar(10)) NOT NULL)

Insert data into Stu_Class_10 table

insert into Stu_Class_10 values(1,'Komal',10);
insert into Stu_Class_10 values(2,'Ajay',10);
insert into Stu_Class_10 values(3,'Rakesh',10);
insert into Stu_Class_10 values(4,'Bhanu',10);
insert into Stu_Class_10 values(5,'Santosh',10);

Stu_Class_10