SQL Server Identity Insert

Galaxy Glossary

How do you temporarily disable the auto-increment feature of an IDENTITY column in SQL Server?

The `IDENTITY_INSERT` command in SQL Server allows you to manually insert values into an identity column. It's useful for populating tables with pre-existing data or for specific scenarios where you need to control the identity seed. However, it's crucial to understand that this feature temporarily disables the automatic incrementing of the identity column.

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Description

The `IDENTITY` property in SQL Server automatically generates unique integer values for columns. This is a powerful feature for creating primary keys and ensuring data integrity. However, sometimes you need to insert data into a table where the identity column already has values. This is where `IDENTITY_INSERT` comes in handy. It temporarily suspends the automatic generation of identity values for a specific table. This allows you to insert values into the identity column, which would otherwise be generated automatically. It's important to note that `IDENTITY_INSERT` is a table-level operation, meaning it affects all rows inserted into the table until you turn it off again. This is a crucial aspect to understand for maintaining data integrity and avoiding unexpected results.Imagine you have a table called `Customers` with an `CustomerID` column that's set as an identity column. If you need to load data from an external source that already contains `CustomerID` values, you can use `IDENTITY_INSERT` to insert those values without conflicts. This is a common scenario when migrating data or loading initial data into a database.Using `IDENTITY_INSERT` is not a permanent solution. It's crucial to turn it off after you've inserted the necessary data to resume the automatic generation of identity values. Failure to do so can lead to unexpected behavior and data inconsistencies in subsequent inserts.In summary, `IDENTITY_INSERT` is a temporary override of the identity column's auto-incrementing behavior. It's a valuable tool for specific data loading scenarios, but it's essential to use it judiciously and remember to turn it off when you're done.

Why SQL Server Identity Insert is important

Understanding `IDENTITY_INSERT` is crucial for data migration and loading pre-existing data into SQL Server tables. It allows you to maintain data integrity and avoid conflicts when dealing with identity columns. It's a vital tool for developers working with data import and export tasks.

Example Usage


-- Create a new job
EXEC msdb.dbo.sp_add_job
    @job_name = N'DailyBackupJob',
    @enabled = 1;

-- Create a step to run a T-SQL script
EXEC msdb.dbo.sp_add_jobstep
    @job_name = N'DailyBackupJob',
    @step_name = N'BackupStep',
    @command = N'BACKUP DATABASE MyDatabase TO DISK = ''C:\Backups\MyDatabase_Full.bak'' WITH NOINIT;',
    @database_name = N'MyDatabase';

-- Schedule the job to run daily at 2 AM
EXEC msdb.dbo.sp_update_job
    @job_name = N'DailyBackupJob',
    @start_step_id = 1,
    @enabled = 1,
    @notify_level_eventlog = 0,
    @notify_level_email = 0,
    @notify_level_netsend = 0,
    @notify_level_page = 0,
    @delete_level = 0,
    @schedule_id = (SELECT schedule_id FROM msdb.dbo.sysjobschedules WHERE name = N'DailySchedule');

-- Create a schedule if it doesn't exist
IF NOT EXISTS (SELECT 1 FROM msdb.dbo.sysjobschedules WHERE name = N'DailySchedule')
BEGIN
    EXEC msdb.dbo.sp_add_schedule
        @schedule_name = N'DailySchedule',
        @active_start_time = N'02:00:00',
        @active_end_time = N'23:59:59',
        @freq_type = 4,
        @freq_interval = 1,
        @freq_subday_type = 0,
        @freq_subday_interval = 0,
        @freq_relative_interval = 0,
        @freq_recurrence_factor = 0,
        @language = N'us_english';
END;

Common Mistakes

Forgetting to turn `IDENTITY_INSERT` off after inserting data.
Using `IDENTITY_INSERT` on the wrong table or column.
Attempting to insert data with incorrect data types for the identity column.

SQL Server Identity Insert

How do you temporarily disable the auto-increment feature of an IDENTITY column in SQL Server?

Description

Why SQL Server Identity Insert is important

Example Usage

Common Mistakes

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