[HttpPost]
        public string GetTableSetCovertJson() {
            DataTable dt = new DataTable("status");
            dt.Columns.AddRange(new DataColumn[] {
                new DataColumn() { ColumnName="Name",DataType=typeof(System.String)},
                new DataColumn() { ColumnName="Age",DataType=typeof(System.Int32)},
                new DataColumn() { ColumnName="Address",DataType=typeof(System.String)},
            });
            dt.Rows.Add(new object[] { "周伯通",98,"重陽宮"});
            dt.Rows.Add(new object[] { "王重陽", 108, "黑洞" });
            dt.Rows.Add(new object[] { "黃藥師", 106, "桃花島" });
            DataTable dt2 = dt.Clone();//克隆表一的結構（所有列）
            dt2.TableName = "Second";
            //表2新增行
            dt2.Rows.Add(new object[] {"郭靖",23,"蒙古大草原" });
            dt2.Rows.Add(new object[] { "黃蓉", 22, "桃花島" });
            //將datable放入dataset中
            //建立dataset
            DataSet ds = new DataSet();
            ds.Tables.AddRange(new DataTable[]{ dt, dt2 });
           
          return   JsonConvert.SerializeObject(ds);
        }
返回的json格式
{"status":
[{"Name":"周伯通","Age":98,"Address":"重陽宮"},
{"Name":"王重陽","Age":108,"Address":"黑洞"},
{"Name":"黃藥師","Age":106,"Address":"桃花島"}],
"Second":
[{"Name":"郭靖","Age":23,"Address":"蒙古大草原"},
{"Name":"黃蓉","Age":22,"Address":"桃花島"}]},