Asp.net - Remove Last Comma Before WHERE In SQL Update

I am manually building up a SQL UPDATE statement out of "SET Column = @param," strings. The problem I have is that the last one of these SET statements before the WHERE, should not contain a comma, as that is as syntax error.

So my code looks like this:

Public Sub Update(byval id as Integer, Optional byval col1 as String = Nothing, Optional byval col2 as Integer = -1)

Dim sqlupdateid As SqlParameter
Dim sqlupdatecol1 As SqlParameter
Dim sqlupdatecol2 As SqlParameter

[Code]....

Can anybody suggest a better algorithm to remove the last comma before the WHERE in the SQL statement, keeping in mind that the number of SET statements before it will vary?

As I'm adding a comma after each set, since another one can follow or not follow, so I have to after building up the UPDATE, go find that last comma and remove it.

So it should look like this:

UPDATE dbo.MyTable SET Col1 = @col1, SET Col2 = @col2 WHERE id = @id