有没有一种简单的方法可以在C#中实现INNER联接、OUTER联接、LEFT OUTER联接，RIGHT OUTER联接

我正在编写一个连接独立数据库系统的c#应用程序。这些系统可以是平面文件数据库、Oracle、Sql、Excel文件等。C#应用程序的工作是提供一个出口，使所有这些源在一个位置可用。因此，基本上，应用程序接受相应数据库系统的查询和连接设置列表，并收集一组结果。

目标是输出一个单独的DataTable，其中包含所有这些查询的结果（取决于设置）。C#是否提供了一种在数据表列表上执行任何联接/并集操作的简单方法？

例如：

Table1:
__________________________________________________________
|tb1_pk_id|   tb1_name    |   tb1_data1   |   tb1_data2   |
|---------|---------------|---------------|---------------|
|    1    | tb1name_blah1 | tb1dat1_blah1 | tb1dat2blah1  |
|    2    | tb1name_blah2 | tb1dat1_blah2 | tb1dat2blah2  |
|    3    | tb1name_blah3 | tb1dat1_blah3 | tb1dat2blah3  |
----------------------------------------------------------- 
Table2:
__________________________________________________________
|tb2_pk_id|   tb2_name    |   tb2_data1   |   tb2_data2   |
|---------|---------------|---------------|---------------|
|    1    | tb2name_blah1 | tb2dat1_blah1 | tb2dat2blah1  |
|    2    | tb2name_blah2 | tb2dat1_blah2 | tb2dat2blah2  |
|    3    | tb2name_blah3 | tb2dat1_blah3 | tb2dat2blah3  |
----------------------------------------------------------- 
Join Results:
__________________________________________________________ _______________________________________________
|tb1_pk_id|   tb1_name    |   tb1_data1   |   tb1_data2   |   tb2_name    |   tb2_data1   |   tb2_data2   |
|---------|---------------|---------------|---------------|---------------|---------------|---------------|
|    1    | tb1name_blah1 | tb1dat1_blah1 | tb1dat2blah1  | tb2name_blah1 | tb2dat1_blah1 | tb2dat2blah1  |
|    2    | tb1name_blah2 | tb1dat1_blah2 | tb1dat2blah2  | tb2name_blah2 | tb2dat1_blah2 | tb2dat2blah2  |
|    3    | tb1name_blah3 | tb1dat1_blah3 | tb1dat2blah3  | tb2name_blah3 | tb2dat1_blah3 | tb2dat2blah3  |
-----------------------------------------------------------------------------------------------------------   

到目前为止，我在网上（这里）找到了以下代码来对所有数据进行合并：

private DataTable MergeAll(IList<DataTable> tables, String primaryKeyColumn)
        {
            if (!tables.Any())
                throw new ArgumentException("Tables must not be empty", "tables");
            if (primaryKeyColumn != null)
                foreach (DataTable t in tables)
                    if (!t.Columns.Contains(primaryKeyColumn))
                        throw new ArgumentException("All tables must have the specified primarykey column " + primaryKeyColumn, "primaryKeyColumn");
            if (tables.Count == 1)
                return tables[0];
            DataTable table = new DataTable("TblUnion");
            table.BeginLoadData(); // Turns off notifications, index maintenance, and constraints while loading data
            foreach (DataTable t in tables)
            {
                table.Merge(t); // same as table.Merge(t, false, MissingSchemaAction.Add);
            }
            table.EndLoadData();
            if (primaryKeyColumn != null)
            {
                // since we might have no real primary keys defined, the rows now might have repeating fields
                // so now we're going to "join" these rows ...
                var pkGroups = table.AsEnumerable()
                    .GroupBy(r => r[primaryKeyColumn]);
                var dupGroups = pkGroups.Where(g => g.Count() > 1);
                foreach (var grpDup in dupGroups)
                {
                    // use first row and modify it
                    DataRow firstRow = grpDup.First();
                    foreach (DataColumn c in table.Columns)
                    {
                        if (firstRow.IsNull(c))
                        {
                            DataRow firstNotNullRow = grpDup.Skip(1).FirstOrDefault(r => !r.IsNull(c));
                            if (firstNotNullRow != null)
                                firstRow[c] = firstNotNullRow[c];
                        }
                    }
                    // remove all but first row
                    var rowsToRemove = grpDup.Skip(1);
                    foreach (DataRow rowToRemove in rowsToRemove)
                        table.Rows.Remove(rowToRemove);
                }
            }
            return table;
        }

这对于执行并集来说很好，但我不知道.NET中是否已经存在一种更简单的方法，可以让我在一组seprate DataTables（而不仅仅是上面代码中的并集）上执行ANY类型的联接或并集，或者我必须自定义每种类型的联接/并集的代码吗？