C#MySqlParameter占位符问题

            StringBuilder strSql=new StringBuilder();
            strSql.Append("select Id,Name from User ");
            strSql.Append(" where Id=@Id");
            OleDbParameter[] parameters = {
                    new OleDbParameter("@Id", OleDbType.Integer,4)
            };
            parameters[0].Value = Id;

            Dong.Model.Unit model=new Dong.Model.Unit();
            DataSet ds=DbHelperOleDb.Query(strSql.ToString(),parameters);
            if(ds.Tables[0].Rows.Count>0)
            {
                return ds.Tables[0].Rows[0];
            }
            else
            {
                return null;
            }

            StringBuilder strSql = new StringBuilder();
            strSql.Append("select id,name,sex from user ");
            strSql.Append(" where id = ?id");

            MySqlParameter[] parameters = {
                    new MySqlParameter("?id", MySqlDbType.Int32)
            };
            parameters[0].Value = (int)id;

            //parameters.ToList().ForEach(i => Console.WriteLine(i.ToString()));

            DataSet ds = DbHelperMySQL.Query(strSql.ToString(),parameters);
    
            if (ds.Tables[0].Rows.Count > 0)
            {
                returnds.Tables[0].Rows[0];
            }
            else
            {
                return null;
            }