They are numbers of reasons due to which run time errrors may be raised during the execution of a pl/sql block.when an error occur,an exception is raised;normal execution is stopped and control is transfered to an exception-handling section of pl/sql program.A specific section can be defined in the program to handle exception.Separate subroutines called exception handlers can be created to perform all exception processing.
HANDLING OF ERRORS
Trapping an Exception:
if the exception is raised in the excetuble section of the block processing branches to the correspondling handlers in the exception section of the block/If pl/sql successfully handle the exception,then the exception does not propagate to the enclosing block or environment.
Propagation of Exception:
if the exception is raised in the executable section of the block and there is no corresponding exception handlers,the pl/sql block terminates with failure and the exception is propagated to the calling environment.
