Hello,

I need help with the code snippet below.  You'll notice that there two different checkbox controls....when they're clicked I would like for them to include a control to be used to filter the given data table, then view it.  With the following code I can do this successfully when only one of the two checkboxes are checked.  I have a feeling that there is a much easier and simple way to do this (switch statement perhaps....?).  Also... what would I need to add in order to make use both the ddList (ddlInstructor & ddlClasses) controls when both are checked?  I hope this makes sense!!     There will be a couple more checkboxes that will include more drop down or text box controls to filter this same table...

 SqlDataAdapter da = new SqlDataAdapter(strSQL2, strConn2);
        DataTable tblClass = new DataTable("ResultTable");

        da.Fill(tblClass);
        DataView vwClass = new DataView(tblClass);

        if (cbIncludeInstructor.Checked == true)
        {

            if (cbIncludeClass.Checked == false)
            {
                vwClass.RowFilter = "Instructor = '" + ddlInstructors.SelectedItem + "'";
            }
        }
        else if (cbIncludeInstructor.Checked == false)
        {
            if (cbIncludeClass.Checked == true)
            {
                vwClass.RowFilter = "ClassName = '" + ddlClasses.SelectedItem + "'";
            }
        }

        GridView2.DataSource = vwClass;
        GridView2.DataBind();

Try with this:

        if (cbIncludeInstructor.Checked)
        {
            vwClass.RowFilter = "Instructor = '" + ddlInstructors.SelectedItem + "'";
            if (cbIncludeClass.Checked)
            {
                vwClass.RowFilter += " & ClassName = '" + ddlClasses.SelectedItem + "'";
            }
        }
        else if (cbIncludeClass.Checked)
        {
            vwClass.RowFilter = "ClassName = '" + ddlClasses.SelectedItem + "'";
        }

void AppendSelectionConditionally(StringBuilder s, string v, bool c)
{
  if (!c)
  {
    return;
  }
  if (s.Length > 0)
  {
    s.Append(" & ");
  }
  s.Append(v);
}

// ...

StringBuilder selection = new StringBuilder();
AppendSelectionConditionally(selection, "Instructor = " + ddlInstructors.SelectedItem, cbIncludeInstructor.Checked);
AppendSelectionConditionally(selection, "ClassName = " + ddlClasses.SelectedItem, cbIncludeClass.Checked);
// ...
vwClass.RowFilter = selection.ToString();

// You must validate any input from the user!!! This code is to demonstrate the principle. It is not safe!

 Would this be its own method or something?  Or would I include this code in the same method where everything else is?

codecorey:

Would this be its own method or something

Yes, it'd be a private internal helper method in the class where the rest of the code is.

When i run the code and select a name ("Charlie Smith", for example) it tells me that I'm missing operand after 'Smith'......  Why is this exception thrown  when I select this name out of the ddlInstructors?      The ddlnstructors list is attached to a datasource .... the first name and last name are joined like "'FirstName+' '+LastName AS Instructor...."     I tried another name in the list and its says missing operand after (whatever the instructor's last name is)    What am I missing?

 Ok, I think I fixed it with:

 StringBuilder selection = new StringBuilder();
        AppendSelectionConditionally(selection, "Instructor = '" + ddlInstructors.SelectedItem + "'", cbIncludeInstructor.Checked);
        AppendSelectionConditionally(selection, "ClassName = '" + ddlClasses.SelectedItem + "'", cbIncludeClass.Checked);
            

 Works fine when just ONE of the check boxes are checked  when I have BOTH checked then hit the search button an exception fires at the 'vwClass.RowFilter = selection.ToString();'   part...... says "The expression contains unsupported operator '&'. "
 

codecorey:

The expression contains unsupported operator '&'.

That's because there is no such operator for this kind of expression. See http://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression(VS.80).aspx . Try 'AND' instead - I'm no ADO.NET guru, the code was just to demonstrate the principle.

'AND' seemed to of worked .......thanks