c# dataTable, Hashtable

Hashtable ht = new Hashtable();
                ht.Add("EMP_NO", "A00003"); //사번
                ht.Add("DEPT_NO", "A02");   //부서코드
                ht.Add("AGE", "42");        //나이

                //ht.Add("EMP_NO", ddl_EMP_NO.SelectedValue); //사번
                //ht.Add("DEPT_NO", txtDept_No.Text.ToString().Trim());   //부서코드
                //ht.Add("AGE", txt);        //나이

                //DataTable
                DataTable dt = new DataTable();
                dt.Columns.Add("EMP_NO", Type.GetType("String"));
                //dt.Columns.Add("DEPT_NO", Type.GetType("String"));
                dt.Columns.Add("AGE", Type.GetType("String"));
                DataRow dr = dt.NewRow();
                dr["EMP_NO"] = "A00003";
                dr["DEPT_NO"] = "A02";
                dr["AGE"] = "42";
                dt.Rows.Add(dr);

 

                //변수
                string emp_no = "A00003";
                string dept_no = "A02";
                string age = "42";