How to use If condition in function? - oracle19c

Question

I am using oracle 19C on windows 10.
I want to create a function return the currency rate base on pass in ID as sample below:
CREATE OR REPLACE NONEDITIONABLE FUNCTION getexchangerate (
oid IN VARCHAR2
) RETURN VARCHAR2 IS
exchangeoid VARCHAR2(36 BYTE) := NULL;
currency VARCHAR2(10 BYTE);
exrate NUMBER(10, 4) := 0.0;
l_ratethb NUMBER(10, 2);
l_rateusd NUMBER(10, 2);
l_rateeur NUMBER(10, 2);
BEGIN
IF ( oid != NULL ) THEN
exchangeoid := regexp_substr(oid, '[^;]+', 1, 1);
currency := regexp_substr(oid, '[^;]+', 1, 2);
END
IF exchangeoid != NULL THEN
SELECT
oid,
ratethb,
rateusd,
rateeur
INTO
exchangeoid,
l_ratethb,
l_rateusd,
l_rateeur
FROM
mexchange
WHERE
oid = exchangeoid;
END
IF CURRENCY !=NULL THEN
IF CURRENCY = 'THB' THEN
exrate := L_RATETHB;
END
IF CURRENCY ='USD' THEN
exrate := L_RATEUSD;
END
IF CURRENCY = 'EUR' THEN
exrate := l_rateeur;
END
END
return exrate;
END getexchangerate;
Above function error:
Error(17,8): PLS-00103: Encountered the symbol "EXCHANGEOID" when expecting one of the following: ;
The pass in value is (534534554xxxxx;USD)
Firstly, need to split oid from currency
then, select the row at oid string.
finally, return the rate base on pass in currency.
I have no idea to complete this function. I am young in PL/SQL.
Can anyone correct or suggest to me, please?
Thank you in advance.

Answer 1

I had changed a bit something like this. It works.
IF CURRENCY IS NOT NULL THEN
IF CURRENCY = 'THB' THEN
exrate := L_RATETHB;
ELSIF CURRENCY ='USD' THEN
exrate := L_RATEUSD;
ELSE CURRENCY = 'EUR' THEN
exrate := l_rateeur;
END IF;
END IF;
Thank you very much for your all suggestion.

Answer 2

From the documentation:
The IF THEN statement has this structure:
IF condition THEN
statements
END IF;
You are getting that error because you finish all your IF blocks with END instead of END IF;. That means it sees this:
...
END
IF exchangeoid != NULL THEN
as END IF and then sees exchangeoid where it expects to see a semicolon completing it.
As #Aleksej pointed out, you are also not handling nulls properly.
So this compiles; see inline comments:
CREATE OR REPLACE NONEDITIONABLE FUNCTION getexchangerate (
oid IN VARCHAR2
) RETURN VARCHAR2 IS
exchangeoid VARCHAR2(36 BYTE) := NULL;
currency VARCHAR2(10 BYTE);
exrate NUMBER(10, 4) := 0.0;
l_ratethb NUMBER(10, 2);
l_rateusd NUMBER(10, 2);
l_rateeur NUMBER(10, 2);
BEGIN
IF ( oid IS NOT NULL ) THEN -- changed != NULL to IS NOT NULL
exchangeoid := regexp_substr(oid, '[^;]+', 1, 1);
currency := regexp_substr(oid, '[^;]+', 1, 2);
END IF; --- added IF;
IF exchangeoid IS NOT NULL THEN -- changed != NULL to IS NOT NULL
SELECT
oid,
ratethb,
rateusd,
rateeur
INTO
exchangeoid,
l_ratethb,
l_rateusd,
l_rateeur
FROM
mexchange
WHERE
oid = exchangeoid;
END IF; --- added IF;
IF CURRENCY IS NOT NULL THEN -- changed != NULL to IS NOT NULL
IF CURRENCY = 'THB' THEN
exrate := L_RATETHB;
END IF; --- added IF;
IF CURRENCY ='USD' THEN
exrate := L_RATEUSD;
END IF; --- added IF;
IF CURRENCY = 'EUR' THEN
exrate := l_rateeur;
END IF; --- added IF;
END IF; --- added IF;
return exrate;
END getexchangerate;
/
You could replace the three currency comparison IF ... END IF; blocks with IF ... ELSIF ... ELSIF ... END IF;, or a CASE statement. You can read about those options in the documentation too.