Introduction:
Identity_Insert is a very important feature in SQL Server. It allows the value of the identity column to be explicitly inserted by the user during the insert operation. This feature is disabled by default, but can be enabled by using the SET IDENTITY_INSERT command.
Enabling Identity_Insert:
Identity_Insert can be enabled by using the SET IDENTITY_INSERT command. The syntax for enabling Identity_Insert is as follows:
SET IDENTITY_INSERT [table_name] ON/OFF
Here, [table_name] is the name of the table where Identity_Insert is being enabled or disabled. By default, Identity_Insert is disabled, so it needs to be explicitly enabled by the user.
Using Identity_Insert:
Identity_Insert is very useful when you need to insert a specific value into the identity column. There are some things that you need to keep in mind when using Identity_Insert:
1) You can only insert a specific value into the identity column when Identity_Insert is enabled.
2) The value that you are inserting into the identity column must be unique. If it is not unique, then the insert operation will fail.
3) Once you have inserted a specific value into the identity column, the next value generated by the identity column will be the value that follows the value you just inserted.
4) When you disable Identity_Insert, the next value generated by the identity column will be the value that would have been generated if you had not inserted a specific value.
Conclusion:
Identity_Insert is a very useful feature in SQL Server. It allows the user to explicitly insert a value into the identity column. This feature is disabled by default, but can be enabled by using the SET IDENTITY_INSERT command. There are some things that you need to keep in mind when using Identity_Insert, but overall, it is a very powerful feature that can save you a lot of time and effort.
