Oracle PL SQL, Simplifying my procedure - sql

Question

I have a following procedure.
PROCEDURE PROC_SELECT_ORDERTBL(
my_cursor OUT SYS_REFCURSOR,
p_ORDER_ID IN VARCHAR2
...
)
BEGIN
IF p_ORDER_ID IS NULL THEN
OPEN my_cursor FOR
[VERY LONG SELECT STATEMENT1]
ELSE
OPEN my_cursor FOR
[VERY LONG SELECT STATEMENT2]
END IF;
END PROC_SELECT_ORDERTBL
select statement 1 and 2 are almost same.
statement2 = statement1 + where clase(checking p_ORDER_ID)
I want to simplifying my procedure like next.
PROCEDURE PROC_SELECT_ORDERTBL(
my_cursor OUT SYS_REFCURSOR,
p_ORDER_ID IN VARCHAR2
...
)
BEGIN
WITH viewData AS
[VERY LONG SELECT STATEMENT1]
IF p_ORDER_ID IS NULL THEN
OPEN my_cursor FOR
viewData
ELSE
OPEN my_cursor FOR
viewData + where clause
END IF;
END PROC_SELECT_ORDERTBL
But this doesn't compile.
----------------------This in my whole procedure code-------------------
-- ORDERTBL 종이식권 주문단위로 조회
PROCEDURE PROC_SELECT_ORDERTBL (
my_cursor OUT SYS_REFCURSOR, -- CURSOR
p_AREA_ID IN VARCHAR2, -- AREA_ID
p_EQP_ID IN VARCHAR2, -- EQP_ID
p_ORDER_ID IN VARCHAR2, -- ORDER_ID
p_date_from IN VARCHAR2, -- yymmdd 조회시작일
p_date_to IN VARCHAR2, -- yymmdd 조회종료일
p_errorcode OUT NUMBER -- error code
) AS
BEGIN
p_errorcode := 0;
IF p_ORDER_ID IS NULL THEN
OPEN my_cursor FOR
SELECT ORD.ORDER_DATE AS 판매일자, ORD.ORDER_TIME AS 판매시간, ORD_ID.ORDER_ID AS 주문번호, TOTAL_SALES AS 판매금액
FROM
(
--판매일자, 판매시간, 판매금액
SELECT ORDER_DATE, ORDER_TIME, SUM(ORDER_FEE) AS TOTAL_SALES
FROM
(
SELECT DISTINCT ORDER_DATE, ORDER_TIME, ORDER_FEE FROM ORDERTBL
WHERE AREA_ID = p_AREA_ID AND EQP_ID = p_EQP_ID AND
ORDER_DATE >= p_date_from AND ORDER_DATE <= p_date_to
)
GROUP BY ORDER_DATE, ORDER_TIME
) ORD
JOIN
(
--판매일자, 판매시간, 주문번호
SELECT ORDER_DATE, ORDER_TIME, MIN(ORDER_ID) AS ORDER_ID
FROM ORDERTBL
WHERE AREA_ID = p_AREA_ID AND EQP_ID = p_EQP_ID AND
ORDER_DATE >= p_date_from AND ORDER_DATE <= p_date_to
GROUP BY ORDER_DATE, ORDER_TIME
) ORD_ID
ON ORD.ORDER_DATE = ORD_ID.ORDER_DATE AND ORD.ORDER_TIME = ORD_ID.ORDER_TIME
ORDER BY ORD.ORDER_DATE, ORD.ORDER_TIME;
ELSE
OPEN my_cursor FOR
SELECT ORD.ORDER_DATE AS 판매일자, ORD.ORDER_TIME AS 판매시간, ORD_ID.ORDER_ID AS 주문번호, TOTAL_SALES AS 판매금액
FROM
(
--판매일자, 판매시간, 판매금액
SELECT ORDER_DATE, ORDER_TIME, SUM(ORDER_FEE) AS TOTAL_SALES
FROM
(
SELECT DISTINCT ORDER_DATE, ORDER_TIME, ORDER_FEE FROM ORDERTBL
WHERE AREA_ID = p_AREA_ID AND EQP_ID = p_EQP_ID AND
ORDER_DATE >= p_date_from AND ORDER_DATE <= p_date_to
)
GROUP BY ORDER_DATE, ORDER_TIME
) ORD
JOIN
(
--판매일자, 판매시간, 주문번호
SELECT ORDER_DATE, ORDER_TIME, MIN(ORDER_ID) AS ORDER_ID
FROM ORDERTBL
WHERE AREA_ID = p_AREA_ID AND EQP_ID = p_EQP_ID AND
ORDER_DATE >= p_date_from AND ORDER_DATE <= p_date_to
GROUP BY ORDER_DATE, ORDER_TIME
) ORD_ID
ON ORD.ORDER_DATE = ORD_ID.ORDER_DATE AND ORD.ORDER_TIME = ORD_ID.ORDER_TIME
WHERE ORD_ID.ORDER_ID = p_ORDER_ID;
END IF;
EXCEPTION
WHEN OTHERS THEN
p_errorcode := SQLCODE;
END PROC_SELECT_ORDERTBL;

Answer 1

You can use CASE construct in the where clause. The logic would be similar to your IF-ELSE condition. But, it is not a good coding practice.
I would go with NVL and DECODE.
Update : The DECODE and NVL parameter values depends on the column data type.
If P_ORDER_ID is NUMBER then use :
WHERE
DECODE(p_order_id, NULL, 0, ORD_ID.ORDER_ID) = NVL(p_ORDER_ID, 0)
else if P_ORDER_ID is VARCHAR2 then use :
WHERE
DECODE(p_order_id, NULL, '0', ORD_ID.ORDER_ID) = NVL(p_ORDER_ID, '0')