DATE COUNTING

Question

hi friends,
I have issue regarding date, that when I am putting simple values of date the result is correct , when I put the add_months and last_day option result is not correct, any idea?
Regards,
1 SELECT COUNT (MAX(TRAN_DATE)) FROM tablename
2 WHERE TO_DATE(TRAN_DATE) BETWEEN '01-NOV-06' AND '16-NOV-06'
3* GROUP BY TRAN_DATE
SQL> /
COUNT(MAX(TRAN_DATE))
16
Second Query :
1 SELECT COUNT (MAX(TRAN_DATE)) FROM tablename
2 WHERE TO_DATE(TRAN_DATE) BETWEEN add_months(last_day(sysdate),-1)+1
3 AND TO_DATE('16-NOV-06')
4* GROUP BY TRAN_DATE
5 /
COUNT(MAX(TRAN_DATE))
15

Answer 1

The "COUNT(MAX(tran_date)) ... GROUP BY tran_date" construction is rather confusing. Isn't it the same as "COUNT(DISTINCT tran_date)" with no GROUP BY? e.g:
SELECT COUNT(DISTINCT tran_date)
FROM   tablename
WHERE  TO_DATE(tran_date) BETWEEN '01-NOV-06' AND '16-NOV-06';Also, what is TO_DATE(tran_date) supposed to do? And '01-NOV-06' isn't a proper date - you are relying on Oracle to guess the format. It would be better as
SELECT COUNT(DISTINCT tran_date)
FROM   tablename
WHERE  TRUNC(tran_date) BETWEEN DATE '2006-11-01' AND DATE '2006-11-16';or if there is an index you want to use on TRAN_DATE, then
SELECT COUNT(DISTINCT tran_date)
FROM   tablename
WHERE  tran_date >= DATE '2006-11-01'
AND    tran_date <  DATE '2006-11-16';