how to add a subtotal rows in oracle? - oracle

Question

i want to add subtotal in between the rows
for example
this the rows and column
NOTE : these three column i am fetching from maintable
a b c
a1 100 100
a2 200 200
a3 300 300
a4 400 400
a5 500 500
a6 600 600
a7 700 700
a8 800 800
a9 900 900
a10 900 900
i want like this
a b c
a1 100 100
a2 200 200
a3 300 300
a4 400 400
subtotal(a1 to a4) 1000 1000
a5 500 500
a6 600 600
subtotal(a5 to a6) 1100 1100
a7 700 700
subtotal(a7) 700 700
a8 800 800
a9 900 900
a10 900 900
subtotal(a8 to a10) 2600 2600
Grandtotal 5400 5400
note : grandtotal = addition of subtotals

Answer 1

Try to combine the use of rollup and grouping functions in this way:
select
decode(grouping(a),1,decode(grouping(subtot_id), 1, 'total', 'subtotal'),a) as a,
sum(b) as b, sum(c) as c
from (
select trunc((rownum-1)/3) as subtot_id, a, b, c
from your_table
order by a
)
group by rollup(subtot_id, a)
I made a sample here

Answer 2

I'm not very experienced in Oracle but I came out with this solution. Required types and function needs to be defined for each table you want to work with. It should be used on small tables because of the time of executing:
CREATE OR REPLACE TYPE row_abc
AS OBJECT (
a varchar2(10),
b integer,
c integer
);
CREATE OR REPLACE TYPE table_abc
AS TABLE OF row_abc;
CREATE OR REPLACE FUNCTION function_name(
report_freq INTEGER := 3
) RETURN table_abc AS
ret table_abc;
counter INTEGER := 0;
CURSOR abc_cursor IS
SELECT row_abc(a, b, c) FROM main_table;
BEGIN
ret := table_abc();
OPEN abc_cursor;
LOOP
counter := counter + 1;
IF counter!=1 AND mod(counter, report_freq)=1 THEN
ret.extend;
SELECT row_abc(
'subtotal',
(SELECT SUM(b) FROM
(SELECT b, rownum rn FROM main_table)
WHERE rn>=counter-report_freq AND rn<counter),
(SELECT SUM(c) FROM
(SELECT c, rownum rn FROM main_table)
WHERE rn>=counter-report_freq AND rn<counter)
) INTO ret(ret.count) FROM dual;
END IF;
ret.extend;
FETCH abc_cursor INTO ret(ret.count);
EXIT WHEN abc_cursor%NOTFOUND;
END LOOP;
CLOSE abc_cursor;
counter := counter - 1;
IF mod(counter, report_freq) != 0 THEN
SELECT row_abc(
'subtotal',
(SELECT SUM(b) FROM
(SELECT b, rownum rn FROM main_table)
WHERE rn>counter-mod(counter, report_freq) AND rn <=counter),
(SELECT SUM(c) FROM
(SELECT c, rownum rn FROM main_table)
WHERE rn>counter-mod(counter, report_freq)AND rn <=counter)
) INTO ret(ret.count) FROM dual;
ret.extend;
END IF;
SELECT row_abc(
'grandtotal',
(SELECT SUM(b) FROM TABLE(ret) WHERE a='subtotal'),
(SELECT SUM(c) FROM TABLE(ret) WHERE a='subtotal')
) INTO ret(ret.count) FROM dual;
RETURN ret;
END function_name;
And you execute it in sql with following line to get your requested output
SELECT * FROM table(function_name(report_freq));
where report_freq is value of frequency of subtotal reports.