Debugging (displaying) SQL command sent to the db by SQLAlchemy

I have an ORM class called Person, which wraps around a person table:

After setting up the connection to the db etc, I run the statement:

people = session.query(Person).all()

The person table does not contain any data (as yet), so when I print the variable people, I get an empty list.

I renamed the table referred to in my ORM class People, to people_foo (which does not exist).

I then run the script again. I was surprised that no exception was thrown when attempting to access a table that does not exist.

I therefore have the following 2 questions:

1. How may I setup SQLAlchemy so that it propagates db errors back to the script?
2. How may I view (i.e. print) the SQL that is being sent to the db engine?

If it helps, I am using PostgreSQL.

[Edit]

I am writing a package. In my __main__.py script, I have the following code (shortened here):

### __main__.py
import common # imports logging and defines logging setup funcs etc

logger = logging.getLogger(__name__)


def main():    
    parser = OptionParser(usage="%prog [options] <commands>",
                          version="%prog 1.0")

    commands = OptionGroup(parser, "commands")

    parser.add_option(
        "-l",
        "--logfile",
        dest="logfile",
        metavar="FILE",
        help="log to FILE. if not set, no logging will be done"
    )

    parser.add_option(
        "--level",
        dest="loglevel",
        metavar="LOG LEVEL",
        help="Debug level. if not set, level will default to low"
    )

    # Set defaults if not specified
    if not options.loglevel:
        loglevel = 1
    else:
        loglevel = options.loglevel

    if not options.logfile:
        logfilename = 'datafeed.log'
    else:
        logfilename = options.logfile

    common.setu