Oracle-Using optional prameters in function? - oracle

Question

I want to add at most three optional parameters to my Oracle function named TEST.
Returned value should be 2.
How to modify my function to make these queries work in a simplest way?
SELECT TEST('eq1','md1') TEST0 FROM DUAL; -- Shows 2 correctly
--How to make these queries also work?
SELECT TEST('eq1','md1','c1') TEST1 FROM DUAL;
SELECT TEST('eq1','md1','c1','d1') TEST2 FROM DUAL;
SELECT TEST('eq1','md1','c1','d1','e1') TEST3 FROM DUAL;
Table and Function are as below.
Table as below
CREATE TABLE T5 (
COL1 VARCHAR2(10),
COL2 VARCHAR2(10),
COL3 VARCHAR2(10),
COL4 VARCHAR2(10),
COL5 VARCHAR2(10),
VAL VARCHAR2(10)
);
INSERT INTO T5 VALUES ('eq1','md1','c1','d1','e1','2');
INSERT INTO T5 VALUES ('eq2','md2','c2','d2','e2','5');
INSERT INTO T5 VALUES ('eq3','md3','c3','d3','e3','3');
My funtion is,
CREATE OR REPLACE FUNCTION TEST
(p1 IN VARCHAR2,
p2 IN VARCHAR2
--How to add optional parameter p3?
--How to add optional parameter p4?
--How to add optional parameter p5?
)
RETURN NUMBER AS V_VALUE VARCHAR2(10);
BEGIN
SELECT(
SELECT VAL FROM T5
WHERE COL1 = p1
AND COL2 = p2
--How to add constraint COL3=p3?
--How to add constraint COL4=p4?
--How to add constraint COL5=p5?
)
INTO V_VALUE
FROM DUAL;
RETURN V_VALUE;
END;
/

Answer 1

You need to define the default value and that's it.
Your function code should look like as follows:
CREATE OR REPLACE FUNCTION TEST (
P1 IN VARCHAR2,
P2 IN VARCHAR2,
P3 IN VARCHAR2 DEFAULT NULL,
P4 IN VARCHAR2 DEFAULT NULL,
P5 IN VARCHAR2 DEFAULT NULL
) RETURN NUMBER AS
V_VALUE VARCHAR2(10);
BEGIN
SELECT
(
SELECT
VAL
FROM
T5
WHERE
COL1 = P1
AND COL2 = P2
AND COL3 = COALESCE(P3, COL3)
AND COL4 = COALESCE(P4, COL4)
AND COL5 = COALESCE(P5, COL5)
)
INTO V_VALUE
FROM
DUAL;
RETURN V_VALUE;
END TEST;
/
Now, all the queries will run:
SELECT TEST('eq1','md1') TEST0 FROM DUAL;
SELECT TEST('eq1','md1','c1') TEST1 FROM DUAL;
SELECT TEST('eq1','md1','c1','d1') TEST2 FROM DUAL;
SELECT TEST('eq1','md1','c1','d1','e1') TEST3 FROM DUAL;
But, Please make sure that order of the passed parameter in the function is not broken.
You can not pass the P5 without passing P4 parameter value except the parameter names are used while calling the function.
Cheers!!