C# How join/union lists of objects and apply sql like functions. Dynamic Linq?

Question

I have list of object arrays (List<object[]> sourcedata) that come from different sources (files, sql, webservices) and I need a way to join/union them, group by, select, where and calculate new columns,...

The user select the sourcedatas (List<object[]>) from a large list of them, and I need a way to transform all of them in one List and I need a way to express that transformation in order the user can write it dinamically depending in his neededs.

I don't know if there is a simple way using dynamic linq. The user who write the expression have knowledge about c# and linq so he could write some linq code at execution time.

Some data would come from Relational databases:

  internal async override Task<IEnumerable<dynamic[]>> ExecuteAsync(IEnumerable<Parameter> parameters)
    {
        List<object[]> returnValue = new List<object[]>();

        using (var conn = new SqlConnection(((MicrosoftSQLServerDataSource)this.DataSource).ConnectionString))
        {
            var queryParametized = this.prepareSqlQuery(this.SqlQuery, parameters);
            using (var query = new SqlCommand(queryParametized.Item1, conn))
            {
                query.Parameters.AddRange(queryParametized.Item2);
                try
                {
                    await conn.OpenAsync();
                    using (DbDataReader reader = await query.ExecuteReaderAsync())
                    {
                        while (reader.Read())
                        {
                            object[] row;
                            if (this.Columns != null && this.Columns.Count > 0)
                            {
                                row = new object[this.Columns.Count];
                                foreach (var col in this.Columns)
                                {
                                    row[col.Index] = this.ConvertData(reader[col.Index], col);
                                }
                            }
                            else
                            {
                                row = new object[reader.FieldCount];
                                for (int i = 0; i < reader.FieldCount; i++)
                                {
                                    row[i] = reader.GetValue(i);
                                }
                            }
                            returnValue.Add(row);

                        }
                    }
                }
                finally
                {
                    if (conn != null && conn.State != System.Data.ConnectionState.Closed)
                        conn.Close();
                }
            }
        }
        return returnValue;
    }

An other from webservices:

    private IEnumerable<dynamic[]> Execute(IEnumerable<Parameter> parameters)
    {
        List<object[]> returnValue = new List<object[]>();

        //Nos logueamos en OBIEE y obtenemos un identificador de sesion 
        //TODO: LLevar un pool de conexiones

       SAWSessionServiceSoapClient sService = new SAWSessionServiceSoapClient();
        //Modificamos la url del servicio web segun este configurada en el dataquery
        sService.Endpoint.Address = new System.ServiceModel.EndpointAddress(this.DataSource.urlWSDL + "?SoapImpl=nQSessionService");

        string sessionID = sService.logon(this.DataSource.User, this.DataSource.Password);

        //Ejecutamos la sql logica del dataquery
        XmlViewServiceSoapClient sqlExecuter = new XmlViewServiceSoapClient();
        //Modificamos la url del servicio web segun este configurada en el dataquery
        sqlExecuter.Endpoint.Address = new System.ServiceModel.EndpointAddress(this.DataSource.urlWSDL + "?SoapImpl=xmlViewService");

        QueryResults resultsData = sqlExecuter.executeSQLQuery(this.getSql(this.LogicalSql, parameters), XMLQueryOutputFormat.SAWRowsetData, new XMLQueryExecutionOptions(), sessionID);

        //Cerramos sesion
        sService.logoff(sessionID);

        //Parseamos el xml de salida
        XDocument doc = XDocument.Load(new System.IO.MemoryStream(System.Text.Encoding.UTF8.GetBytes(resultsData.rowset)));
        XNamespace ns = @"urn:schemas-microsoft-com:xml-analysis:rowset";

        returnValue = (from rows in doc.Root.Descendants(ns + "Row")
                       select (from columns in rows.Elements() select (object)columns.Value).ToArray()
                        ).ToList();

        return returnValue;
    }

And we want let the user merge both data freely.

Any idea? Thanks