IDENTITY (Function) (Transact-SQL)
THIS TOPIC APPLIES TO: SQL Server Azure SQL Database Azure SQL Data Warehouse Parallel Data Warehouse
Is used only in a SELECT statement with an INTO table clause to insert an identity column into a new table. Although similar, the IDENTITY function is not the IDENTITY property that is used with CREATE TABLE and ALTER TABLE.
To create an automatically incrementing number that can be used in multiple tables or that can be called from applications without referencing any table, see Sequence Numbers.
Is the data type of the identity column. Valid data types for an identity column are any data types of the integer data type category, except for the bit data type, or decimal data type.
Is the integer value to be assigned to the first row in the table. Each subsequent row is assigned the next identity value, which is equal to the last IDENTITY value plus the increment value. If neither seed nor increment is specified, both default to 1.
Is the integer value to add to the seed value for successive rows in the table.
Is the name of the column that is to be inserted into the new table.
Returns the same as data_type.
Because this function creates a column in a table, a name for the column must be specified in the select list in one of the following ways:
--(1) SELECT IDENTITY(int, 1,1) AS ID_Num INTO NewTable FROM OldTable; --(2) SELECT ID_Num = IDENTITY(int, 1, 1) INTO NewTable FROM OldTable;
The following example inserts all rows from the Contact table from the AdventureWorks2012database into a new table called NewContact. The IDENTITY function is used to start identification numbers at 100 instead of 1 in the NewContact table.
USE AdventureWorks2012; GO IF OBJECT_ID (N'Person.NewContact', N'U') IS NOT NULL DROP TABLE Person.NewContact; GO ALTER DATABASE AdventureWorks2012 SET RECOVERY BULK_LOGGED; GO SELECT IDENTITY(smallint, 100, 1) AS ContactNum, FirstName AS First, LastName AS Last INTO Person.NewContact FROM Person.Person; GO ALTER DATABASE AdventureWorks2012 SET RECOVERY FULL; GO SELECT ContactNum, First, Last FROM Person.NewContact; GO