Assign parameter name in form

How do I assign a parameter name in forms?

I want to assign a parameter that pulls data from an sql db so am thinking along the line of

<UpdateParameters>
<asp:Parameter Name="email" Type="String" />

But how do I specify the SQL in that? To display the sql in the page I have to use this: <xsl:value-of select="/root/Products/Product/email>

So combining the 2 would I be correct in:
<asp:Parameter Name="email" Type="<xsl:value-of select="/root/Products/Product/email>" />

Then in the form use the email as the id.

Any ideas?

My best idea is that you should post this in the NET forum as it look like a NET question. Maybe people know here, but I would try there.

I have reported this thread to Mods to move to .NET forum.

You can also do that in future by clicking the red triangle icon just next to reputation scales icon against each post

you can't do such thing.
XSLT can be used to render XML into specific HTML output.
nothing more, nothing less.
you can't use XSLT for setting parameters.