Question

How can I set all values in OrderNumber column from 1 to n(when they are ordered by primary key) where n is entries count in table?

EDIT:

Let’s assume we have 3 entries with ID’s 4,7 and 15 … I want to set their OrderValues 1,2 and 3.
I’m using SQL Server 2008.

Answer 1

;WITH x AS (SELECT ID, OrderValues, 
    rn = ROW_NUMBER() OVER (ORDER BY ID)
   FROM dbo.tablename
)
UPDATE x SET OrderValues = rn;

However, why on earth do you want to do this, when you can derive this information using the ROW_NUMBER() function at query time? Storing the values means that they are guaranteed to be out of date and out of sync the moment you insert/update/delete a single row in the table. So unless you plan to run this update after every DML operation (e.g. using a trigger), which isn’t very logical to me, you’re likely much better off getting these row_number values when you run the query vs. storing them in the table.