Albert Lukaszewski

An exception is only explicitly registered when raise is used. Instead of the print statement used in the except clause previously, we can raise an error and update the print statement with the following line of code:
raise MySQLdb.Error
Instead of the friendly statement about an error passing, we get a stack trace that ends as follows:
_mysql_exceptions.Error

except MySQLdb.Error, e:
print "An error has been passed. %s" %e

For exceptions see:
http://python.about.com/od/pythonstandardlibrary/a/lib_exceptions.htm
For warnings visit:
http://python.about.com/od/pythonstandardlibrary/a/lib_warnings.htm
The Python documentation also covers them at:
http://docs.python.org/library/exceptions.html

Each of the previous types can be caught with the DatabaseError type. However, catching them separately allows you to customize responses. For example, you may want the application to fail softly for the user when a ProgrammingError is raised but nonetheless want the exception to be reported to the development team. You can do that with customized exception handling.

Catching different exceptions

To customize which error is caught, we need different except clauses. The basic structure of this strategy is as follows:
try:

except ErrorType1:

except ErrorType2: