两个 DataTable 合并 inner join 内连接

public static DataTable Join(DataTable First, DataTable Second, DataColumn[] FJC, DataColumn[] SJC) { //创建一个新的DataTable DataTable table = new DataTable("Join"); // Use a DataSet to leverage DataRelation using (DataSet ds = new DataSet()) { //把DataTable Copy到DataSet中 ds.Tables.AddRange(new DataTable[] { First.Copy(), Second.Copy() }); DataColumn[] parentcolumns = new DataColumn[FJC.Length]; for (int i = 0; i < parentcolumns.Length; i++) { parentcolumns[i] = ds.Tables[0].Columns[FJC[i].ColumnName]; } DataColumn[] childcolumns = new DataColumn[SJC.Length]; for (int i = 0; i < childcolumns.Length; i++) { childcolumns[i] = ds.Tables[1].Columns[SJC[i].ColumnName]; } //创建关联 DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false); ds.Relations.Add(r); //为关联表创建列 for (int i = 0; i < First.Columns.Count; i++) { table.Columns.Add(First.Columns[i].ColumnName, First.Columns[i].DataType); } for (int i = 0; i < Second.Columns.Count; i++) { //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 if (!table.Columns.Contains(Second.Columns[i].ColumnName)) table.Columns.Add(Second.Columns[i].ColumnName, Second.Columns[i].DataType); else table.Columns.Add(Second.Columns[i].ColumnName + "_Second", Second.Columns[i].DataType); } table.BeginLoadData(); foreach (DataRow firstrow in ds.Tables[0].Rows) { //得到行的数据 DataRow[] childrows = firstrow.GetChildRows(r); if (childrows != null && childrows.Length > 0) { object[] parentarray = firstrow.ItemArray; foreach (DataRow secondrow in childrows) { object[] secondarray = secondrow.ItemArray; object[] joinarray = new object[parentarray.Length + secondarray.Length]; Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length); Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length); table.LoadDataRow(joinarray, true); } } } table.EndLoadData(); } return table; } public static DataTable Join(DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC) { return Join(First, Second, new DataColumn[] { FJC }, new DataColumn[] { SJC }); } /// <summary> /// datatable inner join 合并 /// </summary> /// <param name="First"></param> /// <param name="Second"></param> /// <param name="FJC"></param> /// <param name="SJC"></param> /// <returns></returns> public static DataTable Join(DataTable First, DataTable Second, string FJC, string SJC) { return Join(First, Second, new DataColumn[] { First.Columns[FJC] }, new DataColumn[] { First.Columns[SJC] }); }