Stored Procedure for updating dynamic columns in a table

Question

I have a table with a lot of columns around 30ish
Now I want to create a stored procedure that will update a specific column to a new value.
I the @columname and @newvalue to be the parameters, and an addition @itemId for the WHERE clause so it will update that specific row/data only.
here's my Stored Procedure
USE [db]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[usp_UpdateData]
@itemID int,
@ColumnName varchar(50),
@newValue nvarchar(50)
AS
BEGIN
Update dbo.ProjectAllocation
Set @ColumnName = @newValue
Where itemID = @itemID END
When I pass the following
@ColumnName: UserName
@newValue: NewUserName
@itemID: 1
it doesnt update row with itemID = 1.
How can I do this?
----------------------- Sharepoint Newbie

Answer 1

Did you try my last post method. Its better to use parameterized approach.
Anyway, if you want to change your code,you may need to change as below.....
SET @sql = 'UPDATE dbo.table SET ' + @ColumnName + '=''' + @newValue + ''' WHERE [itemID] = ' + cast(@itemID as varchar(50));