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:          }
原文地址:https://www.cnblogs.com/ppinfo/p/2958724.html