Oracle SQL variable/parameter usage in query - sql

Question

I have this query below and I need to change WHERE conditions depending on QUARTER.
Meaning that I have to copy that query and change the DATE conditions to 06.2020 then use UNION.
I have no idea how can I optimize this query only with SQL because I am not able to DEFINE some variables/parameters in SQL (not using PL/SQL).
SELECT sum(a.limit_amount) as LIMIT,
sum(b.balance_amount) as OUTSTANDING,
'LOAN' as TYPE,
'Q1 2020' as QUARTER
FROM accounts a
left join account_balances b
ON a.account_key = b.account_key
AND b.balance_type_key = 16
AND b.balance_date = last_day(to_date('03.2020', 'MM.YYYY'))
WHERE a.account_close_date > last_day(to_date('03.2020', 'MM.YYYY')) and a.account_open_date <= last_day(to_date('03.2020', 'MM.YYYY'))
Thanks for help

Answer 1

If SQL*Developer, or SQLPlus, you can use the 'substitution variables'.
SELECT sum(a.limit_amount) as LIMIT,
sum(b.balance_amount) as OUTSTANDING,
'LOAN' as TYPE,
'Q1 2020' as QUARTER -- << probably want TO_CHAR('&&1', 'Q YYYY') or similar here
FROM accounts a
left join account_balances b
ON a.account_key = b.account_key
AND b.balance_type_key = 16
AND b.balance_date = last_day(to_date('&&1', 'MM.YYYY'))
WHERE a.account_close_date > last_day(to_date('&&1', 'MM.YYYY')) and a.account_open_date <= last_day(to_date('&&1', 'MM.YYYY'))
When you run this it will prompt you for the value.
If you used just '&1' it would prompt you for each occurence.
'&&1' reuses the value of the first occurence.
You could specify different variables using &1, &2, ...
Also you may used named variable as follows:
To prompt for the date :
ACCEPT dt CHAR PROMPT 'ENter the date (MM.YYYY): '
Or setting the value at declaration:
DEFINE dt='03.2020'
Then:
SELECT sum(a.limit_amount) as LIMIT,
sum(b.balance_amount) as OUTSTANDING,
'LOAN' as TYPE,
'Q1 2020' as QUARTER -- << probably want TO_CHAR('&&dt', 'Q YYYY') or similar here
FROM accounts a
left join account_balances b
ON a.account_key = b.account_key
AND b.balance_type_key = 16
AND b.balance_date = last_day(to_date('&&dt', 'MM.YYYY'))
WHERE a.account_close_date > last_day(to_date('&&dt', 'MM.YYYY')) and a.account_open_date <= last_day(to_date('&&dt', 'MM.YYYY'))

Answer 2

Ok first of all a disclaimer:
As I know nothing about your original query's logic - the query I propose only shows the main logic - and probably will not run as is.
Having said that - the approach would be:
Based on parameters :start_y (start year) and :end_y (end year)
generate a list with all the quarters for those years years_and_quarters.
Join the years_and_quarters with the required table based on quarter start and end dates - and then calculate the sums grouping by year and quarter.
with quarters as
(
select 'Q1' quarter, '03' q_end_date, '01' q_start_date from dual
union
select 'Q2' quarter, '06' q_end_date,'04' q_start_date from dual
union
select 'Q3' quarter, '09' q_end_date,'07' q_start_date from dual
union
select 'Q4' quarter, '12' q_end_date,'10' q_start_date from dual
),
years as
(select :start_y + (level-1) as mydate
from dual
connect by level <= (:end_y - :start_y) +1
),
years_and_quarters as (
select * from years,quarters
order by mydate
),
accounts as (
SELECT a.limit_amount ,
b.balance_amount,
'LOAN' as TYPE, b.balance_date,a.account_open_date,a.account_close_date
FROM accounts a
left join account_balances b
ON a.account_key = b.account_key
AND b.balance_type_key = 16
)
select sum(accounts.limit_amount) as LIMIT,
sum(accounts.balance_amount) as OUTSTANDING,
years_and_quarters.quarter,
accounts.TYPE
from
years_and_quarters,accounts
where
trunc(balance_date) = last_day(to_date(q_end_date||'.'||mydate, 'MM.YYYY'))
and trunc(account_close_date) > last_day(to_date(q_end_date||'.'||mydate, 'MM.YYYY')) and trunc(account_open_date) <= last_day(to_date(q_end_date||'.'||mydate, 'MM.YYYY'))
group by years_and_quarters.mydate,years_and_quarters.quarter

Answer 3

How about just aggregate by the quarter?
SELECT sum(a.limit_amount) as LIMIT,
sum(b.balance_amount) as OUTSTANDING,
'LOAN' as TYPE,
to_char(balance_date, '"Q"Q YYYY') as quarter
FROM accounts a LEFT JOIN
account_balances b
ON a.account_key = b.account_key AND
b.balance_type_key = 16 AND
b.balance_date = LAST_DAY(TRUNC(balance_date, 'Q') + INTERVAL '2' MONTH)
WHERE a.account_close_date > LAST_DAY(TRUNC(balance_date, 'Q') + INTERVAL '2' MONTH) AND
a.account_open_date <= LAST_DAY(TRUNC(balance_date, 'Q') + INTERVAL '2' MONTH)
GROUP BY TRUNC(balance_date, 'Q') ;
Your query seems focused on the last day of the quarter. This arrives at that by adding two months to the start and using LAST_DAY().