Oracle view - sum to variable - sql

Question

How can i shorten the following select statement?
create or replace view V_AMV_PLG_QUOTES_50_MS as
select
sum(NVL(ASK_SIZE,0)) as ASK_VOLUME,
CASE WHEN
sum(CASE WHEN NVL(ASK_SIZE,0)=0 THEN CASE WHEN BASE_CURR_ASK_PRICE=0 THEN 0 ELSE 1 END ELSE ASK_SIZE END)=0 THEN 1
ELSE sum(CASE WHEN NVL(ASK_SIZE,0)=0 THEN CASE WHEN BASE_CURR_ASK_PRICE=0 THEN 0 ELSE 1 END ELSE ASK_SIZE END) END as ASK_PRICE,
EXCHANGE_SK as EXCHANGE_SK,
PRODUCT_SK as PRODUCT_SK,
BUSINESS_DATE as BUSINESS_DATE
from
S_AMV_PLG_QUOTE_AGG quotes
where NVL(BASE_CURR_ASK_PRICE ,0) > 0
group by
EXCHANGE_SK,
PRODUCT_SK,
BUSINESS_DATE
Notice the very long calculation appears twice.. Can i insert it into a variable somehow? And just use the CASE operator on the Variable? (Notice we have a sum function there..)

Answer 1

You can't use create and use a variable within a view. If you just want to avoid repeating the nested case statement, you could move it (and the NVL) into an in-line view:
select
sum(MY_ASK_SIZE) as ASK_VOLUME,
CASE WHEN sum(MY_ASK_PRICE)=0 THEN 1
ELSE sum(MY_ASK_PRICE)
END as ASK_PRICE,
EXCHANGE_SK as EXCHANGE_SK,
PRODUCT_SK as PRODUCT_SK,
BUSINESS_DATE as BUSINESS_DATE
from (
select
EXCHANGE_SK, PRODUCT_SK, BUSINESS_DATE,
NVL(ASK_SIZE,0) as MY_ASK_SIZE,
CASE WHEN NVL(ASK_SIZE,0)=0 THEN
CASE WHEN BASE_CURR_ASK_PRICE=0 THEN 0 ELSE 1 END
ELSE ASK_SIZE
END AS MY_ASK_PRICE
from S_AMV_PLG_QUOTE_AGG quotes
where NVL(BASE_CURR_ASK_PRICE ,0) > 0
)
group by
EXCHANGE_SK,
PRODUCT_SK,
BUSINESS_DATE;
The NVL and case are performed once, and aliased as MY_ASK_SIZE and MY_ASK_PRICE respectively; and those aliases are then used in the outer query, including within the sum.
If you want to avoid repeating the SUM too, move that into the in-line view as well, along with the group-by clause:
select
ASK_VOLUME as ASK_VOLUME,
CASE WHEN ASK_PRICE=0 THEN 1
ELSE ASK_PRICE
END as ASK_PRICE,
EXCHANGE_SK as EXCHANGE_SK,
PRODUCT_SK as PRODUCT_SK,
BUSINESS_DATE as BUSINESS_DATE
from (
select
EXCHANGE_SK, PRODUCT_SK, BUSINESS_DATE,
SUM(NVL(ASK_SIZE,0)) as ASK_VOLUME,
SUM(CASE WHEN NVL(ASK_SIZE,0)=0 THEN
CASE WHEN BASE_CURR_ASK_PRICE=0 THEN 0 ELSE 1 END
ELSE ASK_SIZE
END) AS ASK_PRICE
from S_AMV_PLG_QUOTE_AGG quotes
where NVL(BASE_CURR_ASK_PRICE ,0) > 0
group by
EXCHANGE_SK,
PRODUCT_SK,
BUSINESS_DATE
);
Most of your column aliases are redundant but I've stuck with your pattern.
This is largely cosmetic though; Oracle's optimiser is likely to be clever enough to only perform the actual calculation once anyway, so I wouldn't expect to see much (or any) performance difference.

Answer 2

I used creation of a simple ifZeroReturnOne function:
CREATE OR REPLACE FUNCTION ifZeroReturnOne (expr IN NUMBER)
RETURN NUMBER
IS retval NUMBER;
BEGIN
SELECT CASE WHEN expr=0 THEN 1
ELSE expr END
INTO retval
FROM DUAL;
RETURN (retval);
END;
Than I used in the query:
select sum(NVL(ASK_SIZE,0)) as ASK_VOLUME,
ifZeroReturnOne (sum(CASE WHEN NVL(ASK_SIZE,0)=0 THEN CASE WHEN BASE_CURR_ASK_PRICE=0 THEN 0 ELSE 1 END ELSE ASK_SIZE END) as ASK_PRICE,
EXCHANGE_SK as EXCHANGE_SK,
etc...............
Let me know if you have better suggestions