Oracle Stored Procedure update rows if records exist - stored-procedures

Question

I have following Oracle stored procedure. Either subcode or stylecode is passed in. Currently it is update rows if value is not null. I want to add logic so that make update only if rows are exists on the table, if not, I like to print message like "The subcode xxxx doesn't exists" or "The stylecode xxxx doesn't exists". I don't think merge into works here.
create or replace PROCEDURE "REMOVE_PRICES"
(
RESULT OUT VARCHAR2
, STYLECODE_ IN NUMBER
, SUBCODE_ IN NUMBER
) AS
BEGIN
IF (SUBCODE_ is null AND STYLECODE_ is null)
THEN
raise_application_error(-20005, 'ERROR: Please provide either SUBCODE or STYLECODE!');
END IF;
IF SUBCODE_ IS NOT NULL THEN
UPDATE prices
SET type = null
WHERE subcode=SUBCODE_;
RESULT := SQL%ROWCOUNT || ' price for subcode ' || SUBCODE_ || ' is removed';
ELSIF STYLECODE_ IS NOT NULL THEN
UPDATE prices
SET type = null
WHERE stylecode=STYLECODE_;
RESULT := SQL%ROWCOUNT || ' price for stylecode ' || STYLECODE_ || ' is removed';
END IF;
END REMOVE_PRICES;

Answer 1

You can't only choose to do the update if it will affect rows unless you query with the same conditions first, doing a count; and you could still have a race condition with other sessions that means the data could change between the select and the update, unless you lock the rows. Which all seems a bit excessive and costly.
You can just check the value of SQL%ROWCOUNT and show that message if it is zero, or your current message otherwise:
IF SUBCODE_ IS NOT NULL THEN
UPDATE prices
SET type = null
WHERE subcode=SUBCODE_;
IF SQL%ROWCOUNT = 0 then
RESULT := 'The subcode ' || SUBCODE || ' does not exist';
ELSE
RESULT := SQL%ROWCOUNT || ' price for subcode ' || SUBCODE_ || ' is removed';
END IF;
ELSIF STYLECODE_ IS NOT NULL THEN
UPDATE prices
SET type = null
WHERE stylecode=STYLECODE_;
IF SQL%ROWCOUNT = 0 then
RESULT := 'The stylecode ' || STYLECODE || ' does not exist';
ELSE
RESULT := SQL%ROWCOUNT || ' price for stylecode ' || STYLECODE_ || ' is removed';
END IF;
END IF;