I have a fairly complex query that works fine in ASP.NET, returning the results in a sortable datagrid. Now I just need to be able to filter by date, so I've got two text boxes to collect the start and end date, which I then stick on the end of the URL:

callingURL.aspx/?ID=1302&d1=7/1/2005&d2=7/31/2005

I'm then able to grab the two dates:

dim dRdate1 as string = Request.Item("d1")
dim dRdate2 as string = Request.Item("d2")

But I keep getting operator/operand type mismatches when I go to the page. Here's a simplified version of the code:

dim MySql as string=String.Format("select sdate1,sdate2,Title from Sess " + _    
"where id_code={0} and between(sdate1," & dRdate1 & "," & dRdate2 & "), Request.Item("ID"))

In the BETWEEN() function I've tried putting the variables in quotes, CTOD(), even tried #dRdate1# (most of the examples I could find are for Access). Also tried defining the variables as date instead of string. Also tried not using BETWEEN():

"where id_code={0} and sdate1 >= " & dRdate1 & " and sdate1 <=" & dRdate2, Request.Item("ID"))

I'm probably making this a lot harder than it needs to be. Could someone point out how to get these dates to work? Any suggestions appreciated.