Duplicate Key Error on Primary Key Columns in SQL Server

Q

What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server?

✍: FYIcenter.com

A

If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow duplicate values. The following tutorial exercise gives you a good example:

SELECT * FROM fyi_links
INSERT INTO fyi_links VALUES (101, 
  'sql.fyicenter.com', 
  NULL,
  0,
  '2006-04-30')
GO
Msg 2627, Level 14, State 1, Line 1
Violation of PRIMARY KEY constraint 
   'PK__fyi_links__03317E3D'. Cannot insert duplicate 
   key in object 'dbo.fyi_links'.
The statement has been terminated.

You are getting this error, because value "101" has already been used by an existing row.

⇒ Inserting Multiple Rows with One INSERT Statement in SQL Server

⇐ Providing Column Names in INSERT Statements in SQL Server

⇑ Using INSERT, UPDATE and DELETE Statements in SQL Server

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