Show report horizontally with SQL or PL/SQL - oracle

Question

I am developing a report which should display the data horizontally.
What must be shown is the following:
email#1.com 12/09/2013 11/09/2013 10/09/2013 09/09/2013...
email#2.com 22/03/2013 21/03/2013 12/02/2013 02/01/2013...
Well, I have these data organized in two tables:
Member and Report.
The Member table has the email address and the Report table has dates, and each email can have many different dates.
I can easily retrieve that information vertically:
SELECT M.EMAIL, R.LAST_OPEN_DATE
FROM MEMBER M, REPORT R
WHERE M.MEMBER_ID = R.MEMBER_ID
AND R.STATUS = 1
AND TRUNC(R.LAST_OPEN_DATE) >= TRUNC(SYSDATE) - 120;
However to show the results horizontally is complicated, anyone have a tip or know how I can do this?
I'm using Oracle 11g.

Answer 1

You can get the dates into columns with pivot:
SELECT *
FROM (
SELECT M.EMAIL, R.LAST_OPEN_DATE,
ROW_NUMBER() OVER (PARTITION BY M.MEMBER_ID
ORDER BY R.LAST_OPEN_DATE DESC) AS RN
FROM MEMBER M, REPORT R
WHERE M.MEMBER_ID = R.MEMBER_ID
AND R.STATUS = 1
AND TRUNC(R.LAST_OPEN_DATE) >= TRUNC(SYSDATE) - 120
)
PIVOT (MIN(LAST_OPEN_DATE) FOR (RN) IN (1, 2, 3, 4, 5, 6, 7, 8));
SQL Fiddle.
Essentially this is assigning a number to each report date for each member, and then the pivot is based on that ranking number.
But you'd need to have each of the possible number of days listed; if you can have up to 240 report dates, the PIVOT IN clause would need to be every number up to 240, i.e. IN (1, 2, 3, ..., 239, 240), not just up to eight as in that Fiddle.
If you ever had a member with more than 240 dates you wouldn't see some of them, so whatever high number you pick would have to be high enough to cover every possibility, now and in the foreseeable future. As your query is limited to 120 days, even 240 seems quite high, but perhaps you have more than one per day - in which case there is no real upper limit.
You could potentially have to format each date column individually, but hopefully your reporting layer is taking care of that.
If you just wanted to perform string aggregation using the multiple dates for each email, in you could do this in 11g:
SELECT M.EMAIL,
LISTAGG(TO_CHAR(R.LAST_OPEN_DATE, 'DD/MM/YYYY'), ' ')
WITHIN GROUP (ORDER BY R.LAST_OPEN_DATE DESC)
FROM MEMBER M, REPORT R
WHERE M.MEMBER_ID = R.MEMBER_ID
AND R.STATUS = 1
AND TRUNC(R.LAST_OPEN_DATE) >= TRUNC(SYSDATE) - 120
GROUP BY M.EMAIL;
EMAIL DATES
-------------------- -------------------------------------------
email#1.com 12/04/2014 11/04/2014 10/04/2014 09/04/2014
email#2.com 12/05/2014 02/04/2014 22/03/2014 21/03/2014
SQL Fiddle.
Which is OK for a text report, but not if this query is feeding into a reporting tool.

Answer 2

First of all, number of columns in a query is determined before hand and can't be adjusted by the data. To overcome that, you might be interested in dynamic query
But, in simple static case, you will need to use PIVOT construction.
As a first step, you will need to assign rows to the columns
select EMAIL, row_number() over (partition by email order by last_date) col
from yourtable
then you add "magic" PIVOT:
<your query>
PIVOT
(
max(last_date)
for col in (1, 2, 3, ..., 240)
)