MySQL Stored Procedure Programming: Error Handling

The perfect programmer, living in a perfect world, would always write programs that anticipate every possible circumstance. Those programs would either always work correctly, or fail "Gracefully" by providing comprehensive diagnostic information to the support team and very readable messages to the user. For a certain class of applications - software supporting life support systems or the space shuttle, for instance - this level of perfection is actually a part of the requirements, because any unexpected failure of the software would be catastrophic. However, in the world of business applications, one usually makes certain assumptions about the execution environment - one assumes the MySQL server will be running, that the tables have not been dropped, that the host machine is not on fire, and so on.