User-defined Exception.

User-defined Exception:

• A user-defined exception is an error that is defined by the program.
• The developers to handle the business situations define user-defined exceptions during the execution of the PL/SQL block.
• User defined exceptions are defined by the following two techniques:
• Using a flow control statement RAISE:
• Raise statement transfer the control of the block from the execution part of the PL/SQL block to the exception handing part of the block.

Steps:

1. Declare Exception
2. Raise in Executable section explicitly  using RAISE<Exception_handler_name>;
3. Handle the raised exception.