Testing for existence of a Postgres database

test-for-db.py

from contextlib import closing

def db_exists(cxn, db_name):
    """\
    This takes a connection to a Postgres object and db name and tests whether it
    exists or not.
    """
    with closing(cxn.cursor()) as c:
        c.execute('SELECT COUNT(*) FROM pg_database WHERE datname=%s;', [db_name])
        (count,) = c.fetchone()
        return count > 0

# For more information on the `with` statement and closing function, see these
# pages:
#
# * http://effbot.org/zone/python-with-statement.htm
# * http://www.python.org/dev/peps/pep-0343/
# * http://docs.python.org/release/2.6.7/library/contextlib.html#contextlib.closing
#