Handling Exceptions
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Instead of terminating when an exception occurs, a procedure can respond to and perhaps correct the error condition by handling the exception. When an exception is raised, it does the following:
- Seeks a
WHEN
statement that handles the exception. If one is not found, it terminates execution of theBEGIN … END
block containing the exception and undoes any actions performed in the block. - Backs out one level to the surrounding
BEGIN … END
block and seeks aWHEN
statement that handles the exception, and continues backing out levels until one is found. If noWHEN
statement is found, the procedure is terminated and all its actions are undone. - Performs the ensuing statement or block of statements specified by the
WHEN
statement that handles the exception. - Returns program control to the block in the procedure following the
WHEN
statement.
Note:
An exception that is handled does not return an error message.
An exception that is handled does not return an error message.