@...Thank you for your inputs. I did use the concatenation method before but failed to get the desired result when I used it again recently. The second line in your suggestion reminded me to inject codes in my work aided by Dreamweaver 8. The concatenation, as you advised, together with the following code revision, is producing the desired result.
From (Dreamweaver generated code):
GetSQLValueString($_POST['name_of_hidden_field'], "date")
to:
GetSQLValueString($date, "date")