DropDownList动态添加多个选项

     string sql_dept1 = "select  A.deptno, A.deptno+'/'+DeptName as dept  from HREmpM A,vef_dept B where A.empno='" + uid + "' and A.deptno=B.DeptNo";
            DataSet ds1 = MySqlBase.GetVarsAsDataSet(sql_dept1);
            string sql_dept2 = "select deptno, deptno +'/'+deptname as dept  from  vef_Dept where deptas='" + uid + "'";
            DataSet ds2 = MySqlBase.GetVarsAsDataSet(sql_dept2);
            //DataSet ds = new DataSet();
            //DataTable dt = ds.Tables.Add("dept");
            //dt.Columns.Add("deptno", typeof(string));
            //dt.Columns.Add("deptName", typeof(string));
            object[] var = new object[2];
            ddldept.Items.Add(new ListItem("請選擇", "")); 
            ListItem listItem1 = new ListItem();
            for (int i = 0; i < ds1.Tables[0].Rows.Count;i++ )
            {
                //var[0] = ds1.Tables[0].Rows[i][0].ToString();
                //var[1] = ds1.Tables[0].Rows[i][1].ToString();
                listItem1.Text = ds1.Tables[0].Rows[i][1].ToString();
                listItem1.Value = ds1.Tables[0].Rows[i][0].ToString();
                if (listItem1.Value!=null)
                    ddldept.Items.Add(listItem1);
               // dt.Rows.Add(var);
            }
            object[] var2 = new object[2];
            ListItem listItem2 = new ListItem();
            for (int j = 0; j < ds2.Tables[0].Rows.Count;j++ )
            {
                //var2[0] = ds2.Tables[0].Rows[j][0].ToString();
                //var2[1] = ds2.Tables[0].Rows[j][1].ToString();
                listItem2.Text = ds2.Tables[0].Rows[j][1].ToString();
                listItem2.Value = ds2.Tables[0].Rows[j][0].ToString();
                if (listItem1.Value != null)
                    ddldept.Items.Add(listItem2);
                //dt.Rows.Add(var2);
            }
            //this.ddldept.DataSource = ds;
            //this.ddldept.DataTextField = "deptName";
            //this.ddldept.DataValueField = "deptno";
            //this.ddldept.DataBind();

            if (ddldept.Items.Count > 1)
            {
                ddldept.Attributes.Add("onchange", "showNext(this.options[selectedIndex].value,'ddlRePeo','ddlActPeo');");
            }