如何使用c#.net对6列的数据表行进行分组

本文关键字：数据表 6列 何使用 net | 更新日期: 2023-09-27 18:09:46

需要帮助。我有6列在一个数据表。我已经将其转换为数据视图，并按所有六个对其进行排序，然后相应地更新数据表。当最后4列中的值相同时，我需要分组行，并将它们放在自己的唯一表中，我可以稍后使用，从原始表中删除它们。

我的专栏是:curvennumber, ObjectId, Length, Radius, Delta和Tangent。

感谢您提供的帮助

如何使用c#.net对6列的数据表行进行分组

另一个解决方案

DataTable dt = new DataTable();dt.Columns。AddRange(新数据列[]{新数据列(" curvennumber ")，新数据列("ObjectId")，新数据列("Length")，new dataccolumn ("Radius")， new dataccolumn ("Delta")， new dataccolumn("正切")});dt.Rows。Add(新对象[]{"1","0851"ax,"20"、"20"、"20"、"20"});dt.Rows。Add(新对象[]{"2"、"0852 ab"、"20"、"20"、"20"、"20"});dt.Rows。Add(新对象[]{"3","0853交流","25","32","12","10"});dt.Rows。Add(新对象[]{"4"、"公元0854年","12","31","15"," 20 "});dt.Rows。Add(新对象[]{"5"、"0855 ca"、"20"、"20"、"20"、"20"});dt.Rows。Add(新对象[]{"6"、"公元0856年"、"25","32","12","10"});        //Group by distinct 4 column
      var GroupBy4ColumnDistinct =  dt.Rows.Cast<DataRow>()
        .ToLookup(x => (Convert.ToString(x["Length"]) + Convert.ToString(x["Radius"]) + Convert.ToString(x["Delta"]) + Convert.ToString(x["Tangent"])).GetHashCode())
        .Select(x => new { key = x.Key, values = x.Select(y => Convert.ToString(y["CurveNumber"])).ToList() }).ToList();
        // add new table to dataset. dataset contain 3 table as shown in our sample output
      DataSet ds = new DataSet();
      foreach (var item in GroupBy4ColumnDistinct)
      {
          DataView dv = new DataView(dt);
          dv.RowFilter = " CurveNumber in ( " + string.Join(",", item.values) + " )";
          ds.Tables.Add(dv.ToTable());
      }</pre>

方法—从DataView开始，并使用它的. totable()方法首先获取最后四列的唯一值集合。然后循环查找原始表中的匹配项(来源:https://dotnetfiddle.net/PlAZSi):

)
    // Initial table set up and population
    DataTable originalTable = new DataTable("originaltable");
    originalTable.Columns.Add("CurveNumber", (123).GetType());
    originalTable.Columns.Add("ObjectID", ("String").GetType());
    originalTable.Columns.Add("Length", (123).GetType());
    originalTable.Columns.Add("Radius", (123).GetType());
    originalTable.Columns.Add("Delta", (123).GetType());
    originalTable.Columns.Add("Tangent", (123).GetType());
    originalTable.Rows.Add(new object[] { 1, "0851ax", 20, 20, 20, 20} );
    originalTable.Rows.Add(new object[] { 2, "0852ab", 20, 20, 20, 20} );
    originalTable.Rows.Add(new object[] { 3, "0853ac", 25, 32, 12, 10} );
    originalTable.Rows.Add(new object[] { 4, "0854ad", 12, 31, 15, 20} );
    originalTable.Rows.Add(new object[] { 5, "0855ca", 20, 20, 20, 20} );
    originalTable.Rows.Add(new object[] { 6, "0856ad", 25, 32, 12, 10} );
    // Create a new datatable containing the unique values
    // for the four columns in question
    DataTable uniqueValues = (new DataView(originalTable))
                                .ToTable(true, new string[] {"Length", 
                                                             "Radius", 
                                                             "Delta", 
                                                             "Tangent"});
    // Create a DataSet of DataTables each one containing the grouped
    // rows based on matches on the four columns in question.
    DataSet groupedRows = new DataSet("groupedRows");
    foreach (DataRow uniqueValue in uniqueValues.Rows) {
        // Create the individual table of grouped rows based on the
        // structure of the original table
        DataTable groupTable = originalTable.Clone();
        groupTable.TableName = String.Format("{0}-{1}-{2}-{3}", 
                                             uniqueValue["Length"], 
                                             uniqueValue["Radius"], 
                                             uniqueValue["Delta"], 
                                             uniqueValue["Tangent"]);
        // Fetch the rows from the original table based on matching to the
        // unique combination of four columns
        DataRow[] groupRows = originalTable.Select(String.Format(" Length = {0} AND Radius = {1} AND Delta = {2} AND Tangent = {3} ", 
                                                                 uniqueValue["Length"], 
                                                                 uniqueValue["Radius"], 
                                                                 uniqueValue["Delta"], 
                                                                 uniqueValue["Tangent"]));
        // Add each matched row into the individual grouped DataTable
        foreach (DataRow groupRow in groupRows) {
            groupTable.Rows.Add(groupRow.ItemArray);
        }
        // Finally, add the DataTable to the DataSet
        groupedRows.Tables.Add(groupTable);
    }

我想指出，很可能有一个使用LINQ的更优雅的解决方案。然而，这应该能让你到达你需要的地方。

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