Oracle Plsql Named Programmer Defined Exceptions
Oracle / PLSQL: Named Programmer-Defined Exceptions
This Oracle tutorial explains how to use Named Programmer-Defined Exceptions in Oracle/PLSQL with syntax and examples.
What is a named programmer-defined exception in Oracle?
Sometimes, it is necessary for programmers to name and trap their own exceptions - ones that aren't defined already by PL/SQL. These are called Named Programmer-Defined Exceptions.
Syntax
We will take a look at the syntax for Named Programmer-Defined Exceptions in both procedures and functions.
Syntax for Procedures
The syntax for the Named Programmer-Defined Exception in a procedure is:
CREATE [OR REPLACE] PROCEDURE procedure_name
[ (parameter [,parameter]) ]
IS
[declaration_section]
exception_name EXCEPTION;
BEGIN
executable_section
RAISE exception_name;
EXCEPTION
WHEN exception_name THEN
[statements]
WHEN OTHERS THEN
[statements]
END [procedure_name];Syntax for Functions
The syntax for the Named Programmer-Defined Exception in a function is:
CREATE [OR REPLACE] FUNCTION function_name
[ (parameter [,parameter]) ]
RETURN return_datatype
IS | AS
[declaration_section]
exception_name EXCEPTION;
BEGIN
executable_section
RAISE exception_name;
EXCEPTION
WHEN exception_name THEN
[statements]
WHEN OTHERS THEN
[statements]
END [function_name];Example
Here is an example of a procedure that uses a Named Programmer-Defined Exception:
CREATE OR REPLACE PROCEDURE add_new_order
(order_id_in IN NUMBER, sales_in IN NUMBER)
IS
no_sales EXCEPTION;
BEGIN
IF sales_in = 0 THEN
RAISE no_sales;
ELSE
INSERT INTO orders (order_id, total_sales )
VALUES ( order_id_in, sales_in );
END IF;
EXCEPTION
WHEN no_sales THEN
raise_application_error (-20001,'You must have sales in order to submit the order.');
WHEN OTHERS THEN
raise_application_error (-20002,'An error has occurred inserting an order.');
END;In this example, we have declared a Named Programmer-Defined Exception called no_sales in our declaration statement with the following code:
no_sales EXCEPTION;We've then raised the exception in the executable section of the code:
IF sales_in = 0 THEN
RAISE no_sales;Now if the sales_in variable contains a zero, our code will jump directly to the Named Programmer-Defined Exception called no_sales.
Finally, we tell our procedure what to do when the no_sales exception is encountered by including code in the WHEN clause:
WHEN no_sales THEN
raise_application_error (-20001,'You must have sales in order to submit the order.');We are also using the WHEN OTHERS clause to trap all remaining exceptions:
WHEN OTHERS THEN
raise_application_error (-20002,'An error has occurred inserting an order.');