SQL Identity

Reset Identity column value back to 0

DBCC CHECKIDENT('TableName', RESEED, 0)

At any time, only one table in a session can have the IDENTITY_INSERT property set to ON. 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.

SET IDENTITY_INSERT [TableName] ON

-- Attempt to insert an explicit ID value of 3
INSERT INTO [TableName](id, name) VALUES(3, 'Tea').

SET IDENTITY_INSERT [TableName] OFF