However, the primary key can only be created on columns that are defined as NOT NULL. You can use the ALTER statement to create a primary key. Now we will see how to add Primary Key to existing table in SQL: How to Add Primary Key to Existing Table in SQL? Result: System does not allow inserting new value as 4 is there Course_ID column which is a Primary Key. Insert into COURSE_TSQL_PK values (4,'JAVA') Step 3) Now let’s try Inserting New records with an existing Course_ID which is Primary Key. Note: We can insert duplicate values in the Non-Primary key. Step 2) Verify all Data Inserted successfully by running the Select query. Insert into COURSE_TSQL_PK values (4,'C') Insert into COURSE_TSQL_PK values (3,'SQL') Insert into COURSE_TSQL_PK values (2,'Python') Step 1) Insert 4 rows with different Course_ID Insert into COURSE_TSQL_PK values (1,'SQL') Step 1) Run the Query by clicking on ‘Execute.’Įxample: Let’s see if it allows entering Multiple Records with Same Course ID. Let’s create a Table with One Column as a SQL Primary Key. T-SQL: Create a Primary key while creating a New Table.īelow is the syntax to create table with Primary Key from T-SQLĬolumn2 datatype,CONSTRAINT PRIMARY KEY (Column name) T-SQL: Create Primary while creating a New Table SQL Server Management Studio How to Add Primary Key to Existing Table in SQL?Ģ.How to Create Primary Key in SQL Server.The system will not allow inserting a row with SQL Server Primary Key which already exists in the table.īelow diagram summarizes all the above point for the SQL Primary Key.All the values are unique and Primary key SQL value can uniquely identify each row.Each table can have only one SQL Primary Key.

In other words, every value is unique for Primary Key.

The Primary key is a column or set of columns that are unique. Primary Key is a field or a combination of fields that identify a record uniquely.

Sql server create table