It is important to distinguish the various types of error conditions that might exist in PL/SQL.
A compile time error occurs when there is a problem with PL/SQL code at the time it is
saved to the database. A run time error occurs when a syntactically valid program
encounters a problem during program execution. Many run time errors can be dealt with in the EXCEPTION
section of a PL/SQL block. An exception handler is the special code implemented to handle a given