[Chapter 5] 5.10 PLVexc: Exception Handling

5.10 PLVexc: Exception Handling

The PLVexc (PL/Vision EXCeption handling) package provides generic and powerful exception-handling capabilities. See Chapter 22, Exception Handling for details.

5.10.1 Package constants

c_go CONSTANT CHAR(1) := 'C';: Requests that your program continue (ignore the error). Explained in more detail below.
c_recNgo CONSTANT CHAR(2) := 'RC';: Requests that your program record the error and then continue. Explained in more detail below.
c_stop CONSTANT CHAR(1) := 'H';: Requests that your program be halted if this exception occurs. Explained in more detail below.
c_recNstop CONSTANT CHAR(2) := 'RH';: Requests that your program record the error and then halt. Explained in more detail below.

5.10.2 Package-based exceptions

process_halted EXCEPTION;: Package-specific exception raised when you request a "halt" action in the handler programs.
no_such_table EXCEPTION;
PRAGMA EXCEPTION_INIT (no_such_table, -942);: Predefined system exception for error ORA-942. Saves other developers from dealing with the EXCEPTION_INIT pragma.
snapshot_too_old EXCEPTION;
PRAGMA EXCEPTION_INIT (snapshot_too_old, -1555);: Predefined system exception for error ORA-1555. Saves other developers from dealing with the EXCEPTION_INIT pragma.

5.10.3 Logging exception-handling activity

PROCEDURE log;: Requests that whenever a PLVexc handler is called, a message is sent to the PL/Vision log.
PROCEDURE nolog;: Do not log the handling action when the exception is recorded and handled. with the COMMIT.
FUNCTION logging RETURN BOOLEAN;: Returns TRUE if currently logging PLVexc-based exception handling.

5.10.4 Displaying exceptions

PROCEDURE show;: Requests that error information be displayed to your screen using the p.l procedure.
PROCEDURE noshow;: Turns off display of the error information.
FUNCTION showing RETURN BOOLEAN;: Returns TRUE if PLVexc is currently showing errors.

5.10.5 Rolling back on exception

PROCEDURE rblast;: Requests that a rollback be issued to the most recent savepoint before writing error information to the log (the default).
PROCEDURE rbdef;: Requests that a rollback be issued to the default PLVlog savepoint before writing error information to the log (the default).
PROCEDURE norb;: Turns off issuing of rollback before logging of the error information.
FUNCTION rb RETURN VARCHAR2;: Returns TRUE if PLVexc is currently issuing a rollback.

5.10.6 Exception handlers

PROCEDURE handle
(context_in IN VARCHAR2,
err_code_in IN INTEGER,
handle_action_in IN VARCHAR2,
msg_in IN VARCHAR2 := SQLERRM);: Low-level, generic exception-handling program. This program is called by all other PLVexc handlers, which are overloaded for error number and message.
PROCEDURE recNgo (msg_in IN VARCHAR2 := NULL);
PROCEDURE recNgo (err_code_in IN INTEGER);: High-level exception handler that records and then ignores the error.
PROCEDURE go (msg_in IN VARCHAR2 := NULL);
PROCEDURE go (err_code_in IN INTEGER);: High-level exception handler that ignores the error, but gives you the opportunity to log or display the exception.
PROCEDURE recNstop (msg_in IN VARCHAR2 := NULL);
PROCEDURE recNstop (err_code_in IN INTEGER);: High-level exception handler that records the error and then causes the current program to halt.
PROCEDURE stop (msg_in IN VARCHAR2 := NULL);
PROCEDURE stop (err_code_in IN INTEGER);: High-level exception handler that causes the current program to halt.

5.10.7 Bailing out program execution

PROCEDURE bailout;: Starts the bailout process; the current exception will be propagated out of all exception sections that use PLVexc, regardless of the action handled.
PROCEDURE nobailout;: Turns off the bailout process. PLVexc will not propagate the exception past all PLVexc exception handlers.
FUNCTION bailing_out RETURN BOOLEAN;: Returns TRUE if PLVexc is currently set to bail out when it encounters a bailout error.
PROCEDURE clear_bailouts;: Registers a specific error number as a bailout error.

5.10.8 Managing the list of bailout errors

PROCEDURE clear_bailouts;: Clears the PLVexc list of bailout errors.
PROCEDURE bailout_on (err_code_in IN INTEGER);: Adds an error code to the list that PLVexc treats as bailout errors.
PROCEDURE nobailout_on (err_code_in IN INTEGER);: Removes an error code from the list that PLVexc treats as bailout errors.
FUNCTION bailout_error (err_code_in IN INTEGER) RETURN BOOLEAN;: Returns TRUE if the specified error is a bailout error.


5.9 PLVdyn: Dynamic SQL Operations		5.11 PLVfile: Operating System I/O Manager