The PRIMARY KEY constraint is used to uniquely identifies each record in a database table. The Primary keys in a table contains a unique values. It should contain NULL values. The Table contain a primary key and each table have only primary key.
Understand with Example
The Tutorial illustrate an example to understand SQL PRIMARY KEY Constraint. In this example, we create a table 'Stu_Class_10.The create statement is used to create a table 'Stu_Class_10'.The following SQL creates a PRIMARY KEY on the "Stu_Id" when the" Stu_Class_10" table is created.
Create Table Stu_Class_10
create table Stu_Class_10( Stu_Id integer(2) NOT NULL, Stu_Name varchar(15), Stu_Class varchar(10), PRIMARY KEY(Stu_Id))
Insert data into Stu_Class_10
The insert into statement is used to add the records or rows to the table 'Stu_Class_10'.
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)
If you are facing any programming issue, such as compilation errors or not able to find the code you are looking for.
Ask your questions, our development team will try to give answers to your questions.