column headers in select Union query - sql

Question

I have to select query like the following example :
Select name,
SUM(DECODE(TO_CHAR(Datee,'MM'),'01',PRICE)) JAN_12,
SUM(DECODE(TO_CHAR(Datee,'MM'),'02',PRICE)) FEB_12
from price_list_LastYear
UNION ALL
Select name,
SUM(DECODE(TO_CHAR(Datee,'MM'),'01',PRICE)) JAN_11,
SUM(DECODE(TO_CHAR(Datee,'MM'),'02',PRICE)) FEB_11
from price_list_TwoLastYear.
When I execute the query, In my column header I get name, JAN_12, FEB_12.
I want to combine my results like : name, JAN_11, JAN_12, FEB_11,FEB_12.

Answer 1

Try this:
SELECT P1.name,
SUM(DECODE(TO_CHAR(P1.Datee,'MM'),'01',P1.PRICE)) JAN_12,
SUM(DECODE(TO_CHAR(P1.Datee,'MM'),'02',P1.PRICE)) FEB_12,
SUM(DECODE(TO_CHAR(P2.Datee,'MM'),'01',P2.PRICE)) JAN_11,
SUM(DECODE(TO_CHAR(P2.Datee,'MM'),'02',P2.PRICE)) FEB_11
FROM price_list_LastYear P1
JOIN price_list_TwoLastYear P2
ON P1.nmae = P2.nmae
GROUP BY P1.nmae
If same name doesn't exists in both tables try this:
SELECT N.name,
SUM(DECODE(TO_CHAR(P1.Datee,'MM'),'01',P1.PRICE)) JAN_12,
SUM(DECODE(TO_CHAR(P1.Datee,'MM'),'02',P1.PRICE)) FEB_12,
SUM(DECODE(TO_CHAR(P2.Datee,'MM'),'01',P2.PRICE)) JAN_11,
SUM(DECODE(TO_CHAR(P2.Datee,'MM'),'02',P2.PRICE)) FEB_11
FROM
(
SELECT name FROM price_list_LastYear
UNION
SELECT name FROM price_list_TwoLastYear
) N
LEFT JOIN price_list_LastYear P1
ON N.nmae = P1.name
LEFT JOIN price_list_TwoLastYear P2
ON N.nmae = P2.name
GROUP BY N.name

Answer 2

Try this
SELECT A.*, B,JAN_11, B.FEB_11 FROM (
Select name,
SUM(DECODE(TO_CHAR(Datee,'MM'),'01',PRICE)) JAN_12,
SUM(DECODE(TO_CHAR(Datee,'MM'),'02',PRICE)) FEB_12
from price_list_LastYear
Group By Name) A
LEFT OUTER JOIN (
Select name,
SUM(DECODE(TO_CHAR(Datee,'MM'),'01',PRICE)) JAN_11,
SUM(DECODE(TO_CHAR(Datee,'MM'),'02',PRICE)) FEB_11
from price_list_TwoLastYear
Group By Name) B ON A.name = B.Name
Or
Select name,
SUM(CASE WHEN Yr = '11' THEN DECODE(Mnth,'01',PRICE) ELSE NULL END) JAN_11,
SUM(CASE WHEN Yr = '12' THEN DECODE(Mnth,'01',PRICE) ELSE NULL END) JAN_12,
SUM(CASE WHEN Yr = '11' THEN DECODE(Mnth,'02',PRICE) ELSE NULL END) FEB_11,
SUM(CASE WHEN Yr = '12' THEN DECODE(Mnth,'02',PRICE) ELSE NULL END) FEB_12
from
(
SELECT '12' As yr, name, TO_CHAR(Datee,'MM') Mnth, Price
FROM price_list_LastYear
UNION ALL
SELECT '11' As yr, name, TO_CHAR(Datee,'MM') Mnth, Price
FROM price_list_TwoLastYear
)
GROUP BY Name

Answer 3

If the name does not exist in both tables, then it might be difficult to use a JOIN. So here is a version using UNION ALL and then applying an aggregate function with a CASE expression to transform the data to columns:
SELECT name,
sum(case when Month = 'JAN_12' then price else 0 end) JAN_12,
sum(case when Month = 'FEB_12' then price else 0 end) FEB_12,
sum(case when Month = 'JAN_11' then price else 0 end) JAN_11,
sum(case when Month = 'FEB_11' then price else 0 end) FEB_11
FROM
(
Select name,
PRICE,
case
when TO_CHAR(Datee,'MM') = '01' Then 'JAN_12'
when TO_CHAR(Datee,'MM') = '02' Then 'FEB_12' End Month
from price_list_LastYear
WHERE TO_CHAR(Datee,'MM') in ('01', '02')
UNION ALL
Select name,
PRICE,
case
when TO_CHAR(Datee,'MM') = '01' Then 'JAN_11'
when TO_CHAR(Datee,'MM') = '02' Then 'FEB_11' End Month
from price_list_TwoLastYear
WHERE TO_CHAR(Datee,'MM') in ('01', '02')
) src
GROUP BY name