SQL help: return number of records for each day of last month.

Question

Hi: I have records in the database with a field in the table which contains the Unix epoch time for each record. Letz say the Table name is ED and the field utime contains the Unix epoch time.
Is there a way to get a count of number of records for each day of the last one month? Essentially I want a query which returns a list of count (number of records for each day) with the utime field containing the Unix epoch time. If a particular day does not have any records I want the query to return 0 for that day. I have no clue where to start. Would I need another table which has the list of days?
Thanks
Ray

Answer 1

Peter: thanks. That helps but not completely.
When I run the query to include only records for July using a statement such as following
============
SELECT /*+ FIRST_ROWS */ COUNT(ED.UTIMESTAMP), TO_CHAR((TO_DATE('01/01/1970','MM/DD/YYYY') + (ED.UTIMESTAMP/86400)), 'MM/DD') AS DATA
FROM EVENT_DATA ED
WHERE AGENT_ID = 160
AND (TO_CHAR((TO_DATE('01/01/1970','MM/DD/YYYY')+(ED.UTIMESTAMP/86400)), 'MM/YYYY') = TO_CHAR(SYSDATE-15, 'MM/YYYY'))
GROUP BY TO_CHAR((TO_DATE('01/01/1970','MM/DD/YYYY') + (ED.UTIMESTAMP/86400)), 'MM/DD')
ORDER BY TO_CHAR((TO_DATE('01/01/1970','MM/DD/YYYY') + (ED.UTIMESTAMP/86400)), 'MM/DD');
=============
I get the following
COUNT(ED.UTIMESTAMP) DATA
1 07/20
1 07/21
1 07/24
2 07/25
2 07/27
2 07/28
2 07/29
1 07/30
2 07/31
Some dates donot have any records and so no output. Is there a way to show the missing dates with a COUNT value = 0?
Thanks
Ray