query for all hours in a month?

764672 · Apr 5, 2010 2:53PM

Hello,

I was hoping someone might be able to assist. I need to query for all the hours in a user specified date range (generally a month). For example,
a query such as:
select all hr_end from dual where start_date between '01-feb-2010' and '28-feb-2010'

that returns:

feb 01 2010 01:00
feb 01 2010 02:00
feb 01 2010 03:00
...
feb 28 2010 23:00
feb 28 2010 24:00

Ideally, I want to be able to run this query within a WITH clause such that I can reference the temporary table/ list of hours in a subsequent select statement quickly. Something like:

With
all_hrs_in_month AS
select .....
where start_date between '01-mar-2010' and '31-mar-2010'

I've looked around for similar questions, but have only found ones for all the 'days' in a month using level, connect by, row_num, for which I'm honestly not too familiar with and wasn't clear as to how I could modify to my needs.

Greatly appreciate your help with this request.

- j

Edited by: user12942939 on Apr 5, 2010 12:04 PM

Tubby · Apr 5, 2010 2:58PM

Well, this should give you every hour between your start_date and end_date

select 
  start_date + (1/24 * (level-1)) 
from 
(
  select    
    to_date('01-mar-2010', 'dd-mon-yyyy') as start_date,
    to_date('31-mar-2010', 'dd-mon-yyyy') as end_date
  from dual
) 
connect by level <= (end_date - start_date ) * 24;

And then you'd have to slap that in to your existing query (and outer join to it if you needed data for every hour in the time span).

Centinul · Apr 5, 2010 2:58PM

I've taken that CONNECT BY level concept and changed the units from days to hours.

Hope this helps!

WITH parameters AS
(
        SELECT  TO_DATE('03/01/2010','MM/DD/YYYY') AS START_DAY
        ,       TO_DATE('03/31/2010','MM/DD/YYYY') AS END_DAY
        FROM    DUAL
), hour_range AS
(
        SELECT  START_DAY + (LEVEL-1)/24 AS DT
        FROM    PARAMETERS
        CONNECT BY LEVEL <= (END_DAY - START_DAY + 1)*24 
)
SELECT * FROM HOUR_RANGE
ORDER BY 1

Frank Kulash · Apr 5, 2010 3:06PM

Hi,

Welcome to the forum!

WITH	got_parameters  AS
(
	SELECT	TO_DATE ('01-mar-2010 00:00', 'dd-mon-yyyy hh24:mi')	AS start_date
	,	TO_DATE ('31-mar-2010 23:00', 'dd-mon-yyyy hh24:mi')	AS end_date
	FROM	dual
)
,	all_hrs		AS
(
	SELECT	start_date + ( (LEVEL - 1)
			     / 24
			     )	AS hr
	FROM    got_parameters
	CONNECT BY	LEVEL <= 1 + ( 24
			      	     * (end_date - start_date)
				     )
)
SELECT	  TO_CHAR (hr, 'DD-Mon-YYYY HH24:MI')	AS h
FROM	  all_hrs
ORDER BY  hr
;

Output:

H
-----------------
01-Mar-2010 00:00
01-Mar-2010 01:00
01-Mar-2010 02:00
01-Mar-2010 03:00
...
31-Mar-2010 22:00
31-Mar-2010 23:00

Notice that start_date and end_date don't have to span then entire month; they don't even have to be in the same month.
If you'd rather specify just one parameter (such as a single string containing the month and year):

WITH	got_parameters  AS
(
	SELECT	TRUNC ( TO_DATE (:p_month, 'mon-yyyy')
		      , 'MONTH'
		      )		AS start_date
	,	TRUNC ( ADD_MONTHS ( TO_DATE (:p_month, 'mon-yyyy')
		      		   , 1
				   )
		      , 'MONTH'
		      )		AS end_date
	FROM	dual
)
,	all_hrs		AS
(
	SELECT	start_date + ( (LEVEL - 1)
			     / 24
			     )	AS hr
	FROM    got_parameters
	CONNECT BY	LEVEL <= ( 24		-- NOTE: Not adding 1 here
			      	 * (end_date - start_date)
				 )
)
SELECT	  TO_CHAR (hr, 'DD-Mon-YYYY HH24:MI')	AS h
FROM	  all_hrs
ORDER BY  hr
;

How It Works

SELECT  LEVEL  AS n
FROM    dual
CONNECT BY  LEVEL <= x
;

Produces a result set consiting of the integers 1, 2, 3, ..., x.
There's nothing magical about the dual table; you can use any table AS LONG AS THE TABLE HAS ONLY ONE ROW .
The other examples you saw probably just added this to a starting date, to get successive days, since, in Oracle date arithmetic, dt+n is a DATE n days after dt.
Your case is slightly more complicated, because you want to add hours, not days. Since an hour is 1/24 of a day, we multiply by 24 to find how many integers to genereate, and divide by 24 when adding that number to the base date.

Edited by: Frank Kulash on Apr 5, 2010 3:07 PM

728534 · Apr 5, 2010 4:36PM

Hi,
Wel-come to the forum.

This might help

SELECT (&START_DATE + (LEVEL - 1) / 24) all_hours_month
  FROM DUAL
CONNECT BY LEVEL <= ((&END_DATE+1 - &START_DATE) * 24)+1

Remember 28-feb-2010 24:00 is same as 01-mar-2010 00:00

Cheers!!!
Bhushan

764672 · Apr 5, 2010 4:58PM

Thanks all for your help!!

I was pretty surprised by the speed and completeness of everyone's responses. Really appreciate the help,

j

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