How to LOOP SELECT Query in Oracle?

Question

Hello
I have a query which use a variable (:enddate) and returns a set of data. Lets assume it gives sales totals by account for a given month (specified using the variable :enddate). So the query would look something like :
SELECT ACCOUNT_NO, SUM(SALE_AMT) TOTAL_SALES FROM SCHEMA1.SALES_LINES, :ENDDATE as END_DATE WHERE SALE_DATE BETWEEN addmonths(:ENDDATE,-1) and :ENDDATE
GROUP BY ACCOUNT_NO
Now, currently, I have to run this query each time I need results for a particular date, and thats OK but the problem arises when I need to run this query for an entire year. Then I have to run the query 12 times, passing the date variable each time and re-running the query.
What I would like to do, is to create a loop which covers a time period entered by the user (e.g. user enters 12 months as the total time and 1 month as the period, and the query automatically runs for the previous 12 months, passing :enddate 1 month at a time and then presents the combined results) OR takes a bunch of dates entered in an array, (e.g. :enddate in (JAN-31-2009, Feb-28-2009, MAR-31-2009, APR-30,2009 etc) and runs the query for each of them and presents the results together in one set.
How can I do this using a simple PLSQL loop? I would like to avoid creating a procedure if possible. Sample code will be much appreciated.
BTW, I am using Oracle XE 10g.
Thanks

Answer 1

Hi,
It will be more efficient to get all the results at once, rather than running 12 separate queries.
You can do that without loops or PL/SQL, something like this:
SELECT    account_no
,       TRUNC (sale_date, 'MONTH')     AS mnth
,        SUM (sale_amt)          AS total_sales
FROM        schema1.sales_lines
WHERE       sale_date     >  ADD_MONTHS (:enddate, -12)
AND       sale_date     <= :enddate
GROUP BY  account_no
,            TRUNC (sale_date, 'MONTH')
;Of course, you can do a query like this within PL/SQL if you need to.
If you'd care to post some sample data (CREATE TABLE and INSERT statements) and the results you want from that data, then I could test it.
Simplify as much as possible. For example, instead of 12 sepaarte months, you can post just 2 or 3. Adapting the solution for 12 months should be easy.
In pure SQL, bind varibales can't be DATEs, but you could define the bind variable as a string and use TO_DATE to convert it to a DATE, OR use a substitution variable instead of a bind variable.
The solution above works in all versions Oracle. The way you're using :enddate in the FROM clause, and a function called addmonths (rather than ADD_MONTHS) makes me wonder if you're using Oracle at all.