SET IDENTITY_INSERT (Transact-SQL)
Allows explicit values to be inserted into the identity column of a table.
At any time, only one table in a session can have the IDENTITY_INSERT property set to ON. If a table already has this property set to ON, and a SET IDENTITY_INSERT ON statement is issued for another table, SQL Server returns an error message that states SET IDENTITY_INSERT is already ON and reports the table it is set ON for.
If the value inserted is larger than the current identity value for the table, SQL Server automatically uses the new inserted value as the current identity value.
The setting of SET IDENTITY_INSERT is set at execute or run time and not at parse time.
The following example creates a table with an identity column and shows how the SET IDENTITY_INSERT setting can be used to fill a gap in the identity values caused by a DELETE statement.
USE AdventureWorks2008R2; GO -- Create tool table. CREATE TABLE dbo.Tool( ID INT IDENTITY NOT NULL PRIMARY KEY, Name VARCHAR(40) NOT NULL ) GO -- Inserting values into products table. INSERT INTO dbo.Tool(Name) VALUES ('Screwdriver') INSERT INTO dbo.Tool(Name) VALUES ('Hammer') INSERT INTO dbo.Tool(Name) VALUES ('Saw') INSERT INTO dbo.Tool(Name) VALUES ('Shovel') GO -- Create a gap in the identity values. DELETE dbo.Tool WHERE Name = 'Saw' GO SELECT * FROM dbo.Tool GO -- Try to insert an explicit ID value of 3; -- should return a warning. INSERT INTO dbo.Tool (ID, Name) VALUES (3, 'Garden shovel') GO -- SET IDENTITY_INSERT to ON. SET IDENTITY_INSERT dbo.Tool ON GO -- Try to insert an explicit ID value of 3. INSERT INTO dbo.Tool (ID, Name) VALUES (3, 'Garden shovel') GO SELECT * FROM dbo.Tool GO -- Drop products table. DROP TABLE dbo.Tool GO