SQL中用参数化方式添加新字段

StringBuilder strSql = new StringBuilder();
strSql.Append("@col");
SqlParameter[] parameters = { 
 
                    new SqlParameter("@col", SqlDbType.VarChar,500)};
            parameters[0].Value = string.Format("Alter table RDMS_ProductInfo add  {0} varchar(50) ",rdpims.colEN);
            SQLHelper.RunSql(strSql.ToString(), parameters);