构造查询的时候遇到的问题!

最近我在做一个学生信息系统的查询模块,由于刚刚学Delphi遇到了一些问题:
查询的第一个选择条件是combobox1----政治面貌,性别,专业,等等
在后面呢我设置了5个bomobox分别为combobox2,combobox3,combobox4,combobox5,combobox6,思想是这样的:
比如选择第一条件是政治面貌的时候,那么第二条件则马上显示相应的选项如 团员或者党员,而其他的combobox则隐藏,选择第一条件是性别时候,那么第二条件马上显示男或女,其他的combobox也隐藏(5个combobox组件放在一个坐标上,位置重复)但是在开发的时候碰到了问题,非要点击一下确定按钮,才能实现上述所说的,没有点击确定按钮前,他们的显示状态是最后一个combobox6的显示状态,寻解~!
谢谢各位`!
我的代码如下:
procedure TForm3.Button1Click(Sender: TObject);begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
  case ComboBox1.ItemIndex of
      0:
      begin
          form3.Edit1.Visible:=true;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
          edit1.SetFocus;        if edit1.Text='' then showmessage('请输入查询条件！')
         else
           begin
             ADOTable1.Filtered:=false;
             ADOTable1.Locate('student_ID',trim(edit1.Text),[]);
             DBGrid1.SetFocus;
             if ADOTable1.FieldByName('student_ID').value<>trim(edit1.text)  then
               showmessage('查询无此记录,请确认输入了9位的有效学号')           end;         end;
      1:
         begin
          form3.Edit1.Visible:=true;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
          edit1.SetFocus;
         ADOTable1.Filtered:=false;
          if edit1.Text='' then showmessage('请输入查询条件！')
          else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'student_Name='+QuotedStr(edit1.text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录');
           end;
          end;
      2:
         begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=true;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
          combobox2.SetFocus;
         ADOTable1.Filtered:=false;
          //if edit1.Text='' then showmessage('请输入查询条件！')
          //else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'student_Sex='+QuotedStr(combobox2.text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录');
           end;
           end;
      3:
        begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=true;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
         ADOTable1.Filtered:=false;
          //if edit1.Text='' then showmessage('请输入查询条件！')
         //else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'politi_feature='+QuotedStr(combobox3.text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录');
           end;
          end;
       4:
          begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=true;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=false;
         ADOTable1.Filtered:=false;
          //if edit1.Text='' then showmessage('请输入查询条件！')
          //else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'location='+QuotedStr(combobox4.text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录请确认条件省份例如山东省');
           end;
          end;
       5:begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=true;
         ADOTable1.Filtered:=false;
          //if edit1.Text='' then showmessage('请输入查询条件！')
          //else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'nation='+QuotedStr(combobox5.Text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录请确认条件民族例如汉');
           end;
          end;
       6:
          begin
          form3.Edit1.Visible:=false;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
          form3.ComboBox6.Visible:=true;
          ADOTable1.Filtered:=false;
          //if edit1.Text='' then showmessage('请输入查询条件！')
          //else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'profession='+QuotedStr(combobox6.Text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录请确认条件专业');
           end;
          end;
          7:
          begin
          form3.Edit1.Visible:=true;
          form3.combobox2.visible:=false;
          form3.ComboBox3.visible:=false;
          form3.ComboBox4.Visible:=false;
          form3.ComboBox5.Visible:=false;
         // form3.ComboBox6.Visible:=false;
         ADOTable1.Filtered:=false;
          if edit1.Text='' then showmessage('请输入查询条件！')
          else
          with ADOTable1 do
           begin
           ADOTable1.filter:= 'graduate_school='+QuotedStr(edit1.text);
           ADOTable1.Filtered:=true;
           if ADOTable1.RecordCount=0 then showmessage('查询无此记录请确认条件毕业学校');
           end;
           form3.combobox6.visible:=false;
          end;          end;
       end;end.