RowSet refinement

Rowsets can be defined from other rowsets. In fact rowsets can be defined from themselves. This is called RowSet refinement and can be a powerful way to make your code easier to read.

@output = 
    SELECT
        *,
        Urls.Length AS UrlsLength
    FROM @searchlog;

@output = 
    SELECT 
        Url,
        UrlLength
    FROM @output;