How to get the price for the first service date and last service date - plsqldeveloper

Question

DECLARE
v_in auto_service.vin%TYPE;
v_first auto_service.service_date%TYPE;
v_last auto_service.service_date%TYPE;
v_max auto_service.price%TYPE;
v_total auto_service.price%TYPE;
v_n NUMBER;
CURSOR c_auto
IS
SELECT vin,
COUNT(*) AS no,
MIN(SERVICE_DATE) AS FIRSTprice,
MAX(SERVICE_DATE) AS lastprice,
max(price) as maxprice,
sum(price) as totalprice
FROM auto_service
GROUP BY vin;
BEGIN
OPEN c_auto;
FETCH c_auto INTO v_in,v_n,v_first,v_last,v_total,v_max;
IF c_auto%notfound THEN
dbms_output.put_line('No output');
ELSE
dbms_output.put_line('vin No firstprice lastprice maximumprice totalprice');
LOOP
dbms_output.put_line(rpad(v_in,10) || rpad(v_n,10) || rpad(v_first,10) || rpad(v_last,12) || rpad(v_max,15) || rpad(v_total,5));
FETCH c_auto INTO v_in,v_n,v_first,v_last,v_max,v_total;
EXIT
WHEN c_auto%notfound;
END LOOP;
END IF;
CLOSE c_auto;
END;
To find
the number of services, the first service date and the price for the first service,the last service date and the price for the last service, the maximum price and the service date for the maximum price, and the prices for all services
I got all the other things except price for the first service date and last date of all VIN.

Answer 1

select q.*,
(
select sum(price)
from auto_service x
where x.vin = q.vin
and x.service_date = q.FIRST_DATE
) as FIRST_PRICE,
(
select sum(price)
from auto_service x
where x.vin = q.vin
and x.service_date = q.LAST_DATE
) AS LAST_PRICE
from
(
SELECT vin,
COUNT(*) AS no,
MIN(SERVICE_DATE) AS FIRST_DATE,
MAX(SERVICE_DATE) AS LAST_DATE,
max(price) as maxprice,
sum(price) as totalprice
FROM auto_service
GROUP BY vin
) q
Notice that I renamed the columns you named as FIRSTprice and lastprice to first_date and last_date, since this name is more related to what the column does actually contain.
in second place: i used "select sum(price)" in the subqueries only to handle the possibility that the same car has been serviced twice on the same day. if this should happen, without the sum(), the subquery would extract more than a value and would give you a runtime error. This much less likely to happen if if the date field contains also the time part, not only the date, but it could still happen if your DB contains bad data.
it is up to you if you want to keep that sum() call or if you prefer the db to reveal errors if there are duplicate rows you don't expect