IDENTITY_INSERT is a database setting that allows you to insert or update values in an identity column of a table. This setting is commonly used in Microsoft SQL Server and allows you to manually provide a specific value for an identity column
which is typically auto-generated by the database system.
The purpose of using the IDENTITY_INSERT setting is to allow for more control over the values being inserted into the identity column of a table. By default
the identity column is set to automatically generate a new value each time a new row is inserted into the table. However
there may be situations where you want to override this default behavior and specify a specific value for the identity column.
For example
suppose you have a table of employees with an identity column for employee IDs. If you need to insert a specific employee record with a pre-determined employee ID
you can use the IDENTITY_INSERT setting to manually assign the desired value to the identity column.
To enable the IDENTITY_INSERT setting for a specific table
you would use the following SQL statement:
```
SET IDENTITY_INSERT table_name ON;
```
This statement tells the database system that you will be manually inserting values into the identity column of the specified table. Once you have finished inserting the desired values
you can disable the IDENTITY_INSERT setting by using the following SQL statement:
```
SET IDENTITY_INSERT table_name OFF;
```
It is important to note that you can only have the IDENTITY_INSERT setting enabled for one table at a time within a database. If you attempt to enable the setting for multiple tables simultaneously
you will receive an error message.
Additionally
when using the IDENTITY_INSERT setting
you must ensure that the values you are inserting into the identity column are unique and do not conflict with existing values in the table. Failure to do so can result in data integrity issues and may cause errors when querying the table.
Overall
the IDENTITY_INSERT setting provides a useful mechanism for inserting specific values into identity columns when necessary. By utilizing this setting
you can maintain control over the values being inserted into your database tables and ensure data accuracy and integrity.
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