INSTEAD of UPDATE Triggers in SQL Server

The SQL INSTEAD OF UPDATE trigger is fired before the execution starts. So, you can use this trigger to pass the value for Identity Columns, or Updating different table etc. In this article, we will show you, How to write the INSTEAD OF UPDATE Triggers in SQL Server with an example.

For this demonstration, We are going to use the tables that we have shown below. As you can see from the below screenshot that our Employee table holds 14, and our task is to create an INSTEAD OF UPDATE TRIGGER on this Employee table. And by using this trigger, we want to restrict the records Update

TIP: You can refer INSTEAD OF INSERT article to understand the INSTEAD OF INSERT Trigger, and Instead Of Delete article for INSTEAD OF DELETE Trigger.

and our Employee Table Audit also holds the same 14 records, along with the Server name, Server Instance name, and Insert Time (Audit Information).

NOTE: SQL Instead of Update Triggers can be created on Tables, and Views. In general, we use these triggers on Views

Instead Of UPDATE Triggers in SQL Server Example

In this example, we will show you, How to create an Instead of update Triggers in SQL Server. For instance, if you want to restrict the users from updating the records in the original table, and you want those updated logs in another historical table then you can use this trigger.

Here, we will create a trigger on the Employee table using the CREATE TRIGGER Statement. From the below code snippet you can see that, we are using the INSERT INTO SELECT Statement to select all the records that are inserting into Employee table, and then We are inserting those records into the Audit table.

It means, when the user updates any Employee table record then trigger will insert those records into an audit table, and kept the Employee table unchanged.

-- Example for INSTEAD OF UPDATE Triggers in SQL Server
USE [SQL Tutorial]
GO
CREATE TRIGGER InsteadOfUPDATETriggerExample on [EmployeeTable]
INSTEAD OF UPDATE 
AS DECLARE @ActionPeformed VARCHAR(50)

IF UPDATE(YearlyIncome)
BEGIN
     SET @ActionPeformed = 'Updated Yearly Income'
END
ELSE BEGIN
      SET @ActionPeformed = 'Updated Sales'
END

INSERT INTO [EmployeeTableAudit]( 
       [ID]
      ,[Name]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,[Update Time]
     ,[ActionPerformed])
SELECT ID,
	Name,
	Education,
	Occupation,
	YearlyIncome,
	Sales,
	GETDATE(),
	@ActionPeformed
FROM INSERTED;
PRINT 'We Successfully Fired Our First INSTEAD OF UPDATE Triggers in SQL Server.'
GO

OUTPUT

Let me show you the newly created trigger by opening the Object Explorer -> Go to the SQL Tutorial Database -> Go and expand the Employee Table -> and then expand the Triggers Folder

For the demo purpose, we are updating the Yearly Income as 123,456, and Sales = 5000 for all the records in the Employee table whose Occupation = Professional.

-- SQL INSTEAD OF UPDATE Triggers Example
USE [SQL Tutorial]
GO
UPDATE [EmployeeTable]
	SET [YearlyIncome] = 123456, [Sales] = 5000
	WHERE [Occupation] = N'Professional'

OUTPUT

From the above screenshot, you can see that our trigger is triggered. And, instead of inserting 4 records into the Employee Audit table. Please use the following SQL Query to check the inserted records in the Employee table

-- SQL INSTEAD OF UPDATE Triggers Example
USE [SQL Tutorial]
GO
SELECT [ID]
      ,[Name]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
  FROM [EmployeeTable]

OUTPUT

Though we updated the Employee table, As you can see from the above screenshot, our Employee table is unchanged. Next, check the records in the Employee table Audit using the following query.

-- SQL Server INSTEAD OF UPDATE Triggers Example
USE [SQL Tutorial]
GO

SELECT [Name]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,[ServerName]
      ,[ServerInstanceName]
      ,[Insert Time]
  FROM [EmployeeTableAudit]

OUTPUT

Here, you can see that the trigger has interested 4 new records into Employee audit table

Instead of UPDATE Triggers in SQL Server Example 2

In this example, we will show you, How to Update all the records in the audit table (triggered table) using the Instead of Update Triggers in SQL Server. For this, we are using the MERGE Statement.

-- Example for INSTEAD OF UPDATE Triggers in SQL Server
USE [SQL Tutorial]
GO
CREATE TRIGGER InsteadOfUPDATETriggerExample on [EmployeeTable]
INSTEAD OF UPDATE 
AS DECLARE @ActionPeformed VARCHAR(50)

IF UPDATE(YearlyIncome)
BEGIN
     SET @ActionPeformed = 'Updated Yearly Income'
END
ELSE BEGIN
      SET @ActionPeformed = 'Updated Sales'
END

MERGE [EmployeeTableAudit] AS AuditTab
USING (SELECT * FROM INSERTED) AS Emp
ON AuditTab.ID = emp.ID
WHEN MATCHED THEN
UPDATE SET AuditTab.[Name] = Emp.Name, 
         AuditTab.[Education] = Emp.Education, 
	 AuditTab.[Occupation] = Emp.Occupation,
	 AuditTab.[YearlyIncome] = Emp.YearlyIncome, 
	 AuditTab.[Sales] = Emp.Sales, 
	 AuditTab.[Update Time] = GETDATE(), 
	 AuditTab.[ActionPerformed] = @ActionPeformed;
PRINT 'We Successfully Fired Our Second INSTEAD OF UPDATE Triggers in SQL Server.'
GO

OUTPUT

Next, let me perform updating on the employee table

-- SQL INSTEAD OF UPDATE Triggers Example
USE [SQL Tutorial]
GO
UPDATE [EmployeeTable]
	SET [YearlyIncome] = 111111, 
	    [Sales] = 7777
	WHERE [Occupation] = N'Clerical'

OUTPUT

We don’t have to check the Employee table as we all know that, there will be no updates happened in that table. Next, check with the Employee Audit table.

From the above screenshot, you can see that the trigger has updated all the records.

Instead of UPDATE Triggers in SQL Server Example 3

In this example, we will show you, How to Update all the records in the Employee table using the Instead Of Update Triggers in SQL Server. For this, we are using the INNER JOIN.

-- Example for INSTEAD OF UPDATE Triggers in SQL Server
USE [SQL Tutorial]
GO
CREATE TRIGGER InsteadOfUPDATETriggerExample on [EmployeeTable]
INSTEAD OF UPDATE 
AS 

UPDATE [EmployeeTable] 
 SET [EmployeeTable].[Name] = 'Tutorial Gateway', 
     [EmployeeTable].[Education] = ins.Education,
     [EmployeeTable].[Occupation] = ins.Occupation,
     [EmployeeTable].[YearlyIncome] = ins.YearlyIncome,
     [EmployeeTable].[Sales] = 55555
 FROM [EmployeeTable] 
 INNER JOIN INSERTED AS ins
 ON [EmployeeTable].ID = ins.ID 

PRINT 'We Successfully Fired Our Third INSTEAD OF UPDATE Triggers in SQL Server.'
GO

OUTPUT

ANALYSIS

Below statement will set the name as ‘Tutorial gateway’

SET [EmployeeTable].[Name] = 'Tutorial Gateway',

Next statement will set the Sales amount as 55,555

 [EmployeeTable].[Sales] = 55555

It means, whatever you pass the values to the name, and Sales columns, Instead of Update Trigger will insert the ‘Tutorial gateway’, and 55,555. Or you can say, the trigger will override the values

Next, let me perform updating on the employee table

USE [SQL Tutorial]
GO
UPDATE [EmployeeTable]
	SET [YearlyIncome] = 999999, 
	    [Sales] = 88886
	WHERE [Occupation] = N'Management'

OUTPUT

From the above screenshot, you can see that our instead of update trigger has fired, and also updated all the records in the employee table. Let us see the Employee table