An Identity Column

 

An identity column is one whose value is automatically created by the database engine when a new record is added. This makes sure that each record has a unique value for that field.

To create an identity column in Transact-SQL, after the name and data type of the column, type identity followed by parentheses. Between the parentheses, enter the seed value, followed by a comma, followed by the increment value. Here is an example:

CREATE TABLE Store(
    ItemID int IDENTITY(1, 1) NOT NULL,
    Category nvarchar(50),
    ItemName nvarchar(100) NOT NULL,
    Size nvarchar(20),
    UnitPrice money);
GO

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