如何使选定的下拉选项置为粘性？

Question

I am having problem with sticking the selected option in the drop-down menu in classic asp. If I keep "selected" as shown below, the options values keep on changing in the drop-down bar up to the end of the record in drop-down. In other words, it doesn't matter what you select from the option, it will eventually select the last option in the drop-down list. however it display the correct result. ie it is selecting properly and working fine but doesn't stick on the selected option. Do you think I kept "selected" in wrong spot?

Select: <select class=input>
    <OPTION value=0>-- SELECT --</OPTION>
    <% dim rs
        SQL = "SELECT DISTINCT(brand) as brand FROM tbl"
            SET rs=objConn.Execute(SQL)  

            IF NOT (rs.BOF and rs.EOF) THEN 
                WHILE NOT rs.EOF
                    Response.Write "<option selected value=""" & replace(rs("brand")," & ","@") & """>" & rs("brand") & "</option>"
                    rs.MoveNext
                WEND 
            END IF
                rs.close
                SET rs = nothing
        %>
    </select>

Answer 1

That is happening because in your loop you are setting every option to "selected" and the browser will default to the last option in the list that has that designation.
You need to decide which one you want selected and only include "selected" in that option. If you want the first one (the one you created outside the loop), just don't use "selected" at all.

For example, if you want the brand "Acme" to be selected, do this:

  dim strQueryBrand
  If Request.QueryString("brandID") <> "" Then
     'add some validation here to avoid cross-site scripting issues'
     strQueryBrand = Request.QueryString("brandID")
  End
  dim isSelected = ""
   IF NOT (rs.BOF and rs.EOF) THEN 
        isSelected = ""
        If LCase(strQueryBrand) = LCase(strBrand) then
            isSelected = "selected "
        End If
        WHILE NOT rs.EOF
            Response.Write "<option " & isSelected & "value=""" & replace(rs("brand")," & ","@") & """>" & rs("brand") & "</option>"
            rs.MoveNext
        WEND 
    END IF

Answer 2

It's been a long time since I've looked at ASP - but at first glance it appears that you are setting every option to be selected.

The following doesn't really make sense because you are telling each option that it is the selected one. Ultimately the last option will be the selected one, because it was the one most recently told to be selected.

<select class=input>
    <option selected value="1">1</option>
    <option selected value="2">2</option>
    <option selected value="3">3</option>
    <option selected value="4">4</option>
</select>

Your completed select should only have one option using the "selected" attribute

<select class=input>
    <option value="1">1</option>
    <option selected value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
</select>

Answer 3

You have many options to write your output. I'm guessing you're using a string but brandID gives me the impression and your default value being numeric I'm thinking integer. In any case, follow the following to select your "Selected".

Select: <select class=input onChange="if(options[selectedIndex].value != 0){location='test.asp?list=bybrand&brandID=' + options[selectedIndex].value + '', exit=false;}">
    <% dim rs,strBrand,strQueryBrand
    If Request.QueryString("brandID") <> "" Then
    strQueryBrand = Request.QueryString("brandID")
      If InStr(strQueryBrand,"@") >= 1 Then
         strQueryBrand = Replace(strQueryBrand,"@"," & ")
      End If
    Else
    strQueryBrand = 0
    End If
    '# clean strQueryBrand to prevent SQL injection
        SQL = "SELECT DISTINCT(brand) as brand FROM tbl"
            SET rs=objConn.Execute(SQL)  
            IF NOT (rs.BOF and rs.EOF) THEN 
        If strQueryBrand = 0 Then
        Response.Write "<OPTION value=0 selected>-- SELECT --</OPTION>"
        End If
                WHILE NOT rs.EOF
                strBrand = rs("brand") 
                If LCase(strQueryBrand) = LCase(strBrand) Then
                    Response.Write "<option selected value=""" & replace(rs("brand")," & ","@") & """>" & rs("brand") & "</option>"
                Else            
                    Response.Write "<option value=""" & replace(rs("brand")," & ","@") & """>" & rs("brand") & "</option>"
                End If
                rs.MoveNext
                WEND 
            END IF
                rs.close
                SET rs = nothing
        %>
    </select>

If it is a numeric value you are working with replace the following .

If LCase(strQueryBrand) = LCase(strBrand) Then

with

If (cInt(strQueryBrand) - cInt(strBrand)) = 0 Then

Added another method using PART of Jen R answer. If you have dynamic changing selection content you must make the selection within the loop or it's simply STATIC one answer then you wouldn't need to worry about the Selected because it would be the same each and every time.

Select: <select class=input onChange="if(options[selectedIndex].value != 0){location='test.asp?list=bybrand&brandID=' + options[selectedIndex].value + '', exit=false;}">
<% dim rs,strBrand,strQueryBrand,isSelected
    If Request.QueryString("brandID") <> "" Then
    strQueryBrand = Request.QueryString("brandID") 
      If InStr(strQueryBrand,"@") >= 1 Then
         strQueryBrand = Replace(strQueryBrand,"@"," & ")
      End If
    Else
    strQueryBrand = 0
    End If
'# clean strQueryBrand to prevent injection
    SQL = "SELECT DISTINCT(brand) as brand FROM tbl"
        SET rs=objConn.Execute(SQL)  

        IF NOT (rs.BOF and rs.EOF) THEN 
        If strQueryBrand = 0 Then
        Response.Write "<OPTION value=0 selected>-- SELECT --</OPTION>"
        End If
            WHILE NOT rs.EOF
            strBrand = rs("brand") 
            If LCase(strQueryBrand) = LCase(strBrand) Then
                isSelected = "selected "
            End If           
                Response.Write "<option "&isSelected&" value=""" & replace(rs("brand")," & ","@") & """>" & rs("brand") & "</option>"

            rs.MoveNext
            WEND 
        END IF
            rs.close
            SET rs = nothing
    %>
</select>