You can do that pretty easily with SQLite:

        conn = sqlite3.connect(':memory:')
        conn.execute('''
        create table visits (plano text,
                             "column" text,
                             "row" text,
                             route text)
        ''')
        conn.execute('''
        create table square (plano text,
                             "column" text,
                             "row" text,
                             x int,
                             y int)
        ''')

        for line in infile:
            if line.startswith('#'):
                continue
            plano, column, row, routes = line.split(',')
            column = column.lower()
            x, y = square_coords(plano, column, row)
            conn.execute('''insert into square (plano, "column", "row", x, y)
                                        values (?,     ?,        ?,     ?, ?)
                                        ''',
                                              (plano, column,   row,    x, y))

However, the trouble is that SQL is still kind of verbose, not type-safe, etc. I've been writing up some thoughts on how to do better at http://canonical.org/~kragen/binary-relations.html but I have a long way to go still.