RAISE_APPLICATION_ERROR

• It is a built in procedure in oracle which is used to display the user defined error messages along with the error number whose range is in between -20000 and -20999.
• Whenever a message is displayed using Raise_Application_Error,all previous transactions which are not committed within the PL/SQL block are rolled back automatically(i.e., change due to INSERT,UPDATE OR DELETE statements).
• Raise_Application_Error raised exception but does not handle it.
• Raise_Application_Error is used for the following reasons

                1.To create a unique ID for an user_defined exception.

                2.To make the user defined exception look like an Error.

 The General Syntax to use this Procedure is:

      Raise_Application_Error(Error_number,'Error_message');

• The Error_number must be between -20000 and -20999
• The Error_message is the message you want to display when the error occurs.It can be maximum length of 1 to 2048 characters.