Need Gridview To Display Different Columns Based On New SELECT Statement

I have built an Advanced Search page which allows users to select which columns to return (via checkbox) and to enter search criteria for any of the selected columns (into textboxes). I build the SQL statement from the properties of the controls. Works great.

My problem is getting my gridview control to play nicely. At first I used a SqlDataReader and bound the gridview to it, thus giving me the ability to run new SQL statements through it (with different columns each time). Worked nicely. But, per Microsoft, sorting can only be done if the gridview is bound to a datasource control like the SqlDataSource. So I wrote the code to handle sorting. No big deal; worked nicely. But I could not adjust the column widths programmatically unless bound to a datasource control like the SqlDataSource. And could not figure out a work around.

So, I decided to use the SqlDataSource. Works great. Except, I cannot figure out how to run a new SELECT statement through the SQLDataSource and have the gridview respond accordingly. If I try to return anything other than the exact same columns defined declaratively in the html, it pukes. But I need to be able to return a new selection of columns each time. For example, first time through the user selects columns 1,2,3,4 – the gridview should show those 4 columns. The second time the user selects columns 2,5,7 – the gridview should those 3 columns (and ONLY those 3 columns). Plus support selection and sorting.

I am desperate on this. I've burned 2.5 days researching and testing.  Does anyone have any suggestions?

Thanks,

Brad