• C# 中两个DataTable join 连接


       1:  /// <summary>
       2:          /// 连接两个表
       3:          /// </summary>
       4:          /// <param name="First"></param>
       5:          /// <param name="Second"></param>
       6:          /// <param name="FJC"></param>
       7:          /// <param name="SJC"></param>
       8:          /// <returns></returns>
       9:          public static DataTable JoinTwoTable(DataTable First, DataTable Second, string FJC, string SJC)
      10:          {
      11:              return JoinTwoTable(First, Second, new DataColumn[] { First.Columns[FJC] }, new DataColumn[] { First.Columns[SJC] });
      12:          }
      13:   
      14:   
      15:          /// <summary>
      16:          /// 连接两个表
      17:          /// </summary>
      18:          /// <param name="First"></param>
      19:          /// <param name="Second"></param>
      20:          /// <param name="FJC"></param>
      21:          /// <param name="SJC"></param>
      22:          /// <returns></returns>
      23:          protected static DataTable JoinTwoTable(DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC)
      24:          {
      25:              return JoinTwoTable(First, Second, new DataColumn[] { FJC }, new DataColumn[] { SJC});
      26:          }
      27:   
      28:          /// <summary>
      29:          /// 连接两个Table
      30:          /// </summary>
      31:          /// <param name="First"></param>
      32:          /// <param name="Second"></param>
      33:          /// <param name="FJC"></param>
      34:          /// <param name="SJC"></param>
      35:          /// <returns></returns>
      36:          protected static DataTable JoinTwoTable(DataTable First, DataTable Second, DataColumn[] FJC, DataColumn[] SJC)
      37:          {
      38:   
      39:              //创建一个新的DataTable
      40:              DataTable table = new DataTable("Join");
      41:   
      42:              using (DataSet ds = new DataSet())
      43:              {
      44:   
      45:                  //把DataTable Copy到DataSet中
      46:                  ds.Tables.AddRange(new DataTable[] { First.Copy(), Second.Copy() });
      47:   
      48:                  DataColumn[] parentcolumns = new DataColumn[FJC.Length];
      49:   
      50:                  for (int i = 0; i < parentcolumns.Length; i++)
      51:                  {
      52:                      parentcolumns[i] = ds.Tables[0].Columns[FJC[i].ColumnName];
      53:                  }
      54:   
      55:                  DataColumn[] childcolumns = new DataColumn[SJC.Length];
      56:   
      57:                  for (int i = 0; i < childcolumns.Length; i++)
      58:                  {
      59:                      childcolumns[i] = ds.Tables[1].Columns[SJC[i].ColumnName];
      60:                  }
      61:   
      62:   
      63:                  //创建关联
      64:   
      65:                  DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false);
      66:                  ds.Relations.Add(r);
      67:   
      68:   
      69:                  //为关联表创建列
      70:                  for (int i = 0; i < First.Columns.Count; i++)
      71:                  {
      72:                      table.Columns.Add(First.Columns[i].ColumnName, First.Columns[i].DataType);
      73:                  }
      74:   
      75:                  for (int i = 0; i < Second.Columns.Count; i++)
      76:                  {
      77:                      //看看有没有重复的列,如果有在第二个DataTable的Column的列明后加_Second
      78:                      if (!table.Columns.Contains(Second.Columns[i].ColumnName))
      79:                          table.Columns.Add(Second.Columns[i].ColumnName, Second.Columns[i].DataType);
      80:                      else
      81:                          table.Columns.Add(Second.Columns[i].ColumnName + "_Second", Second.Columns[i].DataType);
      82:                  }
      83:   
      84:   
      85:                  table.BeginLoadData();
      86:   
      87:                  foreach (DataRow firstrow in ds.Tables[0].Rows)
      88:                  {
      89:                      //得到行的数据
      90:                      DataRow[] childrows = firstrow.GetChildRows(r);
      91:   
      92:                      if (childrows != null && childrows.Length > 0)
      93:                      {
      94:                          object[] parentarray = firstrow.ItemArray;
      95:   
      96:                          foreach (DataRow secondrow in childrows)
      97:                          {
      98:                              object[] secondarray = secondrow.ItemArray;
      99:   
     100:                              object[] joinarray = new object[parentarray.Length + secondarray.Length];
     101:   
     102:                              Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);
     103:   
     104:                              Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);
     105:   
     106:                              table.LoadDataRow(joinarray, true);
     107:                          }
     108:                      }
     109:                  }
     110:   
     111:                  table.EndLoadData();
     112:              }
     113:   
     114:   
     115:              return table;
     116:   
     117:          }
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  • 原文地址:https://www.cnblogs.com/ppinfo/p/2958724.html
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