Getting Record Count From Date Range - IDE: PLSQL Developer

Question

I would like to count the number of member records that fall within a specified date range based on the members effective and expiration dates and their 'elg_code'. I have posted the SQL for some sample data. What I would like to see returned is three columns of counts where the members eff_date exp_date fall within the date range specified by the SQL and have an Elg_code of ' ' (one blank space).
So, what I would like is all members with elg_code ' ' where there eff_dt and exp_dt range falls within APR 2012, MAY 2012 & JUN 2012. So, based on the sample data I posted, Mark, where his elg_code record is ' ', his eff_dt is 1/1/2011 and his exp_dt is within APR 2012 (4/30/2012). Mark's range falls within APR 2012, but not MAY or JUNE of 2012. Marty would tally for both APR and MAY since his eff_dt is before MAY 2012 and his exp is within MAY 2012. etc..
Based on the data below, the results should look like:
APR MAY JUN
4 3 2
APR should have FRANK, MARK, MARTY, MARY,
MAY should have FRANK, MARTY, MARY
JUN should have FRANK and MARY
NOAM and JEAN should not show up as their records with elg_code ' ' do not have eff_dt and exp_dt records that fall within APR-JUN 2012.
So what I tried without success as it appears I have some kind of Cartesian issue (?), is:
select count(m1.mbr_name) APR,
count(m2.mbr_name) MAY,
count(m3.mbr_name) JUN
from mbr2 m1,
mbr2 m2,
mbr2 m3
where m1.eff_dt < '01-may-2012'
and m1.exp_dt > '01-apr-2012'
and m1.elg_code = ' '
and m2.eff_dt < '01-jun-2012'
and m2.exp_dt > '01-may-2012'
and m2.elg_code = ' '
and m3.eff_dt < '01-jul-2012'
and m3.exp_dt > '01-jun-2012'
and m3.elg_code = ' '
Below is the DML
Thanks for any assistance!
create table mbr2 (mbr_name varchar(10), grpid varchar(1), eff_dt date, exp_dt date, elg_code varchar(1))
commit
insert into mbr2 values ('MARK', 'A', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('04-30-2012', 'MM-DD-YYYY'), ' ')
insert into mbr2 values ('MARK', 'A', to_date('05-01-2012', 'MM-DD-YYYY'), to_date('12-31-2013', 'MM-DD-YYYY'), 'C')
insert into mbr2 values ('MARTY', 'A', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('05-31-2012', 'MM-DD-YYYY'), ' ')
insert into mbr2 values ('MARTY', 'A', to_date('06-01-2012', 'MM-DD-YYYY'), to_date('12-31-2013', 'MM-DD-YYYY'), 'C')
insert into mbr2 values ('FRANK', 'B', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('06-30-2012', 'MM-DD-YYYY'), ' ')
insert into mbr2 values ('FRANK', 'B', to_date('07-01-2012', 'MM-DD-YYYY'), to_date('12-31-2013', 'MM-DD-YYYY'), 'C')
insert into mbr2 values ('MARY', 'B', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('06-30-2012', 'MM-DD-YYYY'), ' ')
insert into mbr2 values ('MARY', 'B', to_date('07-01-2012', 'MM-DD-YYYY'), to_date('12-31-2013', 'MM-DD-YYYY'), 'C')
insert into mbr2 values ('JEAN', 'C', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'), ' ')
insert into mbr2 values ('JEAN', 'C', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'), 'C')
insert into mbr2 values ('NOAM', 'D', to_date('07-01-2012', 'MM-DD-YYYY'), to_date('12-31-2013', 'MM-DD-YYYY'), ' ')
commit

Answer 1

Hi,
Here's one way:
WITH     all_months     AS
     SELECT     LEVEL                         AS month_num
     ,     ADD_MONTHS (first_month, LEVEL - 1)     AS month_begin
     ,     ADD_MONTHS (first_month, LEVEL)           AS next_month_begin
     FROM     (
               SELECT  TO_DATE ('04-01-2012', 'MM-DD-YYYY')     AS first_month
               ,     TO_DATE ('06-01-2012', 'MM-DD-YYYY')     AS last_month
               FROM     dual
     CONNECT BY     level     <= 1 + MONTHS_BETWEEN (last_month, first_month)
SELECT    COUNT (CASE WHEN month_num = 1 THEN 1 END)     AS month_1
,       COUNT (CASE WHEN month_num = 2 THEN 1 END)     AS month_2
,       COUNT (CASE WHEN month_num = 3 THEN 1 END)     AS month_3
FROM       all_months  a
JOIN       mbr2        m  ON  a.month_begin       <= m.exp_dt
                        AND a.next_month_begin      >  m.eff_dt
WHERE     m.elg_code      = ' '
;This assumes you know how many months will be in the output. If you want to derive that from the data, or to give the columns meaningful aliases (such as APR-2011 instead of MONTH_1), then you'll need dynamic SQL (to get separate columns for each month) or string aggregation (if you don't mind one big VARCHAR2 column, formatted to look like several columns). See {message:id=3527823}
If you don't mind modifying the query a little every time you run it, you can hard-code the number of columns and the month names. In the main query, put exactly as many lines as you need, with the alias you want at the end. That is, instead of
,       COUNT (CASE WHEN month_num = 2 THEN 1 END)     AS month_2say
,       COUNT (CASE WHEN month_num = 2 THEN 1 END)     AS may_2012I'm not sure exactly what the problem was with the query you posted. It looks like this site cut off parts of the query.
One thing that is definitely a mistake is that you're comparing DATE columns to VARCHAR2 literals. Never compare a DATE to a VARCHAR2; compare DATEs to DATEs (or compare VARCHAR2s to VARCHAR2s). So instead of
and m1.exp_dt > '01-apr-2012'you should say
and m1.exp_dt > TO_DATE ('01-apr-2012', 'dd-mon-yyyy')Thanks for posting the CREATE TABLE and INSERT statements; that's very helpful.
Edited by: Frank Kulash on Jun 26, 2012 3:32 PM