将两个DataTable合并——DataTable.Merge 方法

private static void DemonstrateMergeTable()
{
    DataTable table1 = new DataTable("Items");

    // Add columns
    DataColumn idColumn = new DataColumn("id", typeof(System.Int32));
    DataColumn itemColumn = new DataColumn("item", typeof(System.Int32));
    table1.Columns.Add(idColumn);
    table1.Columns.Add(itemColumn);

    // Set the primary key column.
    table1.PrimaryKey = new DataColumn[] { idColumn };

    // Add RowChanged event handler for the table.
    table1.RowChanged += new
        System.Data.DataRowChangeEventHandler(Row_Changed);

    // Add ten rows.
    DataRow row;
    for (int i = 0; i <= 9; i++)
    {
        row = table1.NewRow();
        row["id"] = i;
        row["item"] = i;
        table1.Rows.Add(row);
    }

    // Accept changes.
    table1.AcceptChanges();
    PrintValues(table1, "Original values");

    // Create a second DataTable identical to the first.
    DataTable table2 = table1.Clone();

    // Add column to the second column, so that the
    // schemas no longer match.
    table2.Columns.Add("newColumn", typeof(System.String));

    // Add three rows. Note that the id column can't be the
    // same as existing rows in the original table.
    row = table2.NewRow();
    row["id"] = 14;
    row["item"] = 774;
    row["newColumn"] = "new column 1";
    table2.Rows.Add(row);

    row = table2.NewRow();
    row["id"] = 12;
    row["item"] = 555;
    row["newColumn"] = "new column 2";
    table2.Rows.Add(row);

    row = table2.NewRow();
    row["id"] = 13;
    row["item"] = 665;
    row["newColumn"] = "new column 3";
    table2.Rows.Add(row);

    // Merge table2 into the table1.
    Console.WriteLine("Merging");
    table1.Merge(table2, false, MissingSchemaAction.Add);
    PrintValues(table1, "Merged With table1, schema added");
}

private static void Row_Changed(object sender,
    DataRowChangeEventArgs e)
{
    Console.WriteLine("Row changed {0}\t{1}", e.Action,
        e.Row.ItemArray[0]);
}

private static void PrintValues(DataTable table, string label)
{
    // Display the values in the supplied DataTable:
    Console.WriteLine(label);
    foreach (DataRow row in table.Rows)
    {
        foreach (DataColumn col in table.Columns)
        {
            Console.Write("\t " + row[col].ToString());
        }
        Console.WriteLine();
    }
}

方法2：多个for循环遍历 利用主键value值相同合并

 public string GetShengAnakysis(StatisticQuery model)
        {
            string strJson1 = AccessibilityConcAnalysis("PM25",model.beginTime,model.endTime, model.Stns.Split(',').Length);
            string strJson2 = AccessibilityRateAnalysis("EG", model.beginTime, model.endTime, model.Stns.Split(',').Length);
            string strJson3 = AccessibilityRateAnalysis("HPS", model.beginTime, model.endTime, model.Stns.Split(',').Length);
            DataTable dtPM = JsonConvert.DeserializeObject(strJson1);
            DataTable dtEG = JsonConvert.DeserializeObject(strJson2);
            DataTable dtHPS = JsonConvert.DeserializeObject(strJson3);
            List list = new List();
            for (int i = 0; i < dtPM.Rows.Count; i++)
            {
                ShengAnakysis obj = new ShengAnakysis();
                for (int j = 0; j < dtEG.Rows.Count; j++)
                {
                    for (int k = 0; k < dtHPS.Rows.Count; k++)
                    {
                        if (dtPM.Rows[i]["City"].ToString()== dtEG.Rows[j]["City"].ToString() && dtPM.Rows[i]["City"].ToString() == dtHPS.Rows[k]["City"].ToString() && dtEG.Rows[j]["City"].ToString()== dtHPS.Rows[k]["City"].ToString()) {
                            obj.City = dtPM.Rows[i]["City"].ToString();
                            obj.KHValue = dtPM.Rows[i]["KHValue"].ToString();
                            obj.SofarAvg = dtPM.Rows[i]["SofarAvg"].ToString();
                            obj.OverDayAvg = dtPM.Rows[i]["OverDayAvg"].ToString();
                            obj.OverDayTq = dtPM.Rows[i]["OverDayTq"].ToString();

                            obj.EGKHValue = dtEG.Rows[j]["KHValue"].ToString();
                            obj.EGSofarAvg = dtEG.Rows[j]["SofarAvg"].ToString();
                            obj.EGOverDayAvg = dtEG.Rows[j]["OverDayAvg"].ToString();
                            obj.EGOverDayTq = dtEG.Rows[j]["OverDayTq"].ToString();
                            obj.EGSyDayRate = dtEG.Rows[j]["SyDayRate"].ToString();
                            obj.EGLastYearDayRate = dtEG.Rows[j]["LastYearDayRate"].ToString();

                            obj.HPSKHValue = dtHPS.Rows[k]["KHValue"].ToString();
                            obj.HPSSofarAvg = dtHPS.Rows[k]["SofarAvg"].ToString();
                            obj.HPSOverDayAvg = dtHPS.Rows[k]["OverDayAvg"].ToString();
                            obj.HPSOverDayTq = dtHPS.Rows[k]["OverDayTq"].ToString();

                            obj.SortId = dtPM.Rows[i]["SortId"].ToString();
                        }
                        continue;
                    }
                }
                list.Add(obj);
            }


            return JsonConvert.SerializeObject(list);
        }