The EXCEPTION Section
The EXCEPTION section is an optional part in any PL/SQL block. If this section is omitted and errors are encountered, the block will be terminated. Some errors that are encountered may not justify the immediate termination of a block, so the EXCEPTION section can be used to handle specified errors or user-defined exceptions in an orderly manner. Exceptions can be user defined although many exceptions are predefined by Oracle.
An exception is an error that is raised during processing when running a PL/SQL program.
Exceptions are raised in a block by using the command RAISE. Exceptions can be raised explicitly ...