Select/Option/Value on change using Classic ASP

I tried to create a select option value on change using classic ASP but it didn't work. No error but when I view, nothing pop up from second select.

I like to select student name from first select box, if it matches, then second box shows course name, and third box shows Semester.

I like to store student names and StudentID into DB.

Can anyone help?

Students table

StudentID   Firstname   Lastname
-------------------------------
01         AAA         LN1
02         BBB         LN2
03         CCC         LN3

Class table

Course    CourseID StudentID Semester-------------------------------------
History   C01      01        Spring
History   C01      01        Summer
Math      C02      02        Spring
Math      C02      02        Fall           

<%Set oRs = Server.CreateObject("adodb.recordset")
                            strSQL =" SELECT StudentID, Firstname, Lastname FROM Students Where StudentID = '"& Request.ServerVariables("LOGON_Student")&"'"
                            oRs.Open strSQL, myConn
                            sName = oRs("Lastname")&", "& oRs("Firstname")ifnot oRs.eof then%><select name="Students" id="selectStudent" onChange="this.form.action='default.asp';this.form.submit();"><option value="<%= oRs(0) %>"<%if trim(request.Form("Students"))= trim(oRs(0))then response.write " selected "endif%>><%= sName %></option><option value="<%= oRs("StudentID") %>" hidden></option></select><%endif%><%if request.Form("Students")<>""then
                            strSQL =" SELECT Course FROM Class WHERE StudentID = '"& request.Form("StudentID")&"'"Set oRs = Server.CreateObject("adodb.RecordSet")
                            oRs.Open strSQL, myConnifnot oRs.eof then%><select name="Class" id="selectClass" onChange="this.form.action='default.asp';this.form.submit();"><%dountil oRs.eof  %><option value="<%= oRs(0) %>"<%if trim(request.Form("Class"))= trim(oRs(0))then response.write " selected "endif%>><%= oRs(0)%></option><% oRs.MoveNextloop%></select><%endifendif%><%if request.Form("Class")<>""then
                            strSQL =" SELECT Semester FROM Class WHERE Course = '"& request.Form("Course")&"'"Set oRs = Server.CreateObject("adodb.RecordSet")
                            oRs.Open strSQL, myConnifnot oRs.eof then%><select name="Class" id="selectClass" onChange="this.form.action='default.asp';this.form.submit();"><%dountil oRs.eof  %><option value="<%= oRs(0) %>"<%if trim(request.Form("Class"))= trim(oRs(0))then response.write " selected "endif%>><%= oRs(0)%></option><% oRs.MoveNextloop%></select><%endifendif%>