string query = "select * from worker_table;";
            query += "select id_worker, name_tag from cross_table, tag_table where id_tag = id;";
            SQLiteDataAdapter da = new SQLiteDataAdapter(query, conn.ConnectionString);
            DataSet ds = new DataSet();
            da.Fill(ds);
            ds.Relations.Add("relation", ds.Tables[0].Columns[0], ds.Tables[1].Columns[0]);
            MainGrid.DataSource = new BindingSource(ds,"Table");
            ChildGrid.DataSource = new BindingSource(MainGrid.DataSource,"relation");

            string query = "select * from worker_table;";
            query += "select * from cross_table;"
            query += "select * from tag_table";