用另外一个query或者adoquery控件控制显示combobox2的内容:
adoquery2.Close;
adoquery2.SQL.Clear;
adoquery2.SQL.Add('select * from students where name= ''' + combobox1.Items[combobox1.itemindex] + '''');
adoquery2.Open;
combobox2.Items.Clear;
combobox2.Text:= adoquery2.fieldbyname('sex').AsString;