While researching Oracle Analytics, I came across this query:
select an_id,
a_date,
min(a_date) over (
partition by an_id, trunc(a_date)
order by a_date
range between (2.5/24) preceding and (2.5/24) following
) mn,
max(a_date) over (
partition by an_id, trunc(a_date)
order by a_date
range between (2.5/24) preceding and (2.5/24) following
) mx
from a_table
I believe this finds the min and max dates for a given an_id and a_date within a 2.5 hour period.
My question is why does this comparison between a_date (a date) and 2.5/24 (a number) work and how can it be modified for ranges of days, months, or years?
The date type allows arithmetic where a unit of 1 is a day, so SYSDATE + 1 is tomorrow.
For example, try select to_char(sysdate + 1/24, 'DD-MON-YY HH:MM:SS') from dual -> 1 hour from now.
Here are the docs that talk about that specific analytic construct to give some foundational info and add to what jwilson mentioned.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/functions001.htm#i97640
It's probably clearer to use intervals to specify window ranges:
http://download.oracle.com/docs/cd/B19306%5F01/server.102/b14200/functions104.htm#i89943
SELECT last_name,
hire_date,
salary,
SUM(salary) OVER (ORDER BY hire_date
RANGE NUMTOYMINTERVAL(1,'year') PRECEDING) AS t_sal
FROM employees;
Related
How can I find the amount for an interval of 100 days?
I got this option:
SELECT SUM(AMN)
OVER (PARTITION BY ID
ORDER BY DATE RANGE BETWEEN INTERVAL '100' DAY(3) PRECEDING
AND CURRENT ROW) S1
FROM ddd
You did it correctly. The other way is correlated subquery, like below. But window functions are designed exactly for such purposes and you should use them instead of subqueries. They are much faster.
SQLFiddle demo
select id, date_, amn,
sum(amn) over(partition by id order by date_
range between interval '100' day(3) preceding
and current row) s1,
(select sum(amn)
from ddd d2
where ddd.id = d2.id
and date_ between ddd.date_ - interval '100' day(3)
and ddd.date_) s2
from ddd
I need to bring the day immediately preceding date in Oracle using a truncate but not how. He was using the following line but bring me some records for the current day of execution and should not be. Neceisto only the previous day; investigation found the truncate with dates in Oracle but not how to use it.
and fnxs.FECHA_INGRESO BETWEEN (TO_CHAR (SYSDATE-1, 'DD-MON-YY')) AND (TO_CHAR (SYSDATE, 'DD-MON-YY'));
I appreciate your help
Using BETWEEN with dates in Oracle is generally a bad idea. I see it all the time, and most of the time people get it wrong (like in the accepted answer above). Even when they fully understand that the two dates are included, they still make logical errors because they forget about timestamps.
The OP is asking for yesterday dates. The following sql shows that today falls within "BETWEEN TRUNC( SYSDATE ) - 1 AND TRUNC( SYSDATE )"
with adate as (
select trunc(sysdate) today from dual
) select today from adate where today between trunc(sysdate) -1
and trunc(sysdate);
16-Apr-15 00:00:00
[returns the record for today]
I find it easier to be correct with dates when you're more explicit about the end points:
SELECT * from your_table
WHERE fnxs.FECHA_INGRESO >= TRUMC(SYSDATE) - 1
AND fnxs.FECHA_INGRESO < TRUNC(SYSDATE);
Upon looking closer, the OP's date-like column might be a VARCHAR2 (could still be a date that was implicitly cast in the comparison he gave). If it is a VARCHAR, then it needs to be converted first (using an appropriate format string):
SELECT * FROM your_table
WHERE TO_DATE(fnxs.FECHA_INGRESO, 'DD-MON-YY') >= TRUMC(SYSDATE) - 1
AND TO_DATE(fnxs.FECHA_INGRESO, 'DD-MON-YY') < TRUNC(SYSDATE);
Assuming your column is of type DATE
SELECT *
FROM TABLE_NAME
WHERE FECHA_INGRESO BETWEEN TRUNC( SYSDATE ) - 1
AND TRUNC( SYSDATE );
If it is a character string then:
SELECT *
FROM TABLE_NAME
WHERE TO_DATE( FECHA_INGRESO, 'DD-MON-YY' )
BETWEEN TRUNC( SYSDATE ) - 1
AND TRUNC( SYSDATE );
I need to fetch 200 rows a month per year randomly sampled for each month from this table in Oracle 10g:
Documents
--------------------------------------
Doc_ID Date
95687 25-AUG-12
99283 21-SEP-12
87654 10-AUG-12
97111 14-SEP-12
I've seen the SAMPLE() function but not sure how to do the other parts of the criteria.
Perhaps something like this:
select doc_id
, date
from ( select doc_id
, date
, row_number() over (partition by trunc(date, 'MM')
order by dbms_randon.value ) as rn
from your_table )
where rn <= 200
order by date, doc_id ;
The analytic ROW_NUMBER() function produces a number for each record grouped by month (achieved by truncating the date with the 'MM' mask). Ordering by DBMS_RANDOM will randomise the sort order. Remember to initialise DBMS_RANDOM before running the query to get a truly random sort order.
Find out more.
I have an account where interest is debited corresponding to each account as below
amount Date
2 01-01-2012
5 02-01-2012
2 05-01-2012
1 07-01-2012
If the total credit in the account is 8. Ineed a query to find till what dates interest the credit amount can adjust.
Here the query should give output as 02-01-2012(2+5 < 8). I know this can be handled through cursor. But is there any method to write this as a single query in ORACLE.
SELECT pdate
FROM (
SELECT t.*,
LAG(date) OVER (ORDER BY date) AS pdate
8 - SUM(amount) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS diff
FROM mytable t
ORDER BY
date
)
WHERE diff < 0
AND rownum = 1
Not knowing the structure of your table, here's a guess:
SELECT date from your_table
GROUP BY AMOUNT
HAVING SUM(AMOUNT) < 8
Note: this is LESS THAN 8. Change the conditional as appropriate.
Doesn't do the (2+5)<8 thing yet:
select max(cum_sum), max(date)
from (
select date,
sum(amount) over (order by date) cum_sum
) where cum_sum < 8
The question I need to answer is this "What is the maximum number of page requests we have ever received in a 60 minute period?"
I have a table that looks similar to this:
date_page_requested date;
page varchar(80);
I'm looking for the MAX count of rows in any 60 minute timeslice.
I thought analytic functions might get me there but so far I'm drawing a blank.
I would love a pointer in the right direction.
You have some options in the answer that will work, here is one that uses Oracle's "Windowing Functions with Logical Offset" feature instead of joins or correlated subqueries.
First the test table:
Wrote file afiedt.buf
1 create table t pctfree 0 nologging as
2 select date '2011-09-15' + level / (24 * 4) as date_page_requested
3 from dual
4* connect by level <= (24 * 4)
SQL> /
Table created.
SQL> insert into t values (to_date('2011-09-15 11:11:11', 'YYYY-MM-DD HH24:Mi:SS'));
1 row created.
SQL> commit;
Commit complete.
T now contains a row every quarter hour for a day with one additional row at 11:11:11 AM. The query preceeds in three steps. Step 1 is to, for every row, get the number of rows that come within the next hour after the time of the row:
1 with x as (select date_page_requested
2 , count(*) over (order by date_page_requested
3 range between current row
4 and interval '1' hour following) as hour_count
5 from t)
Then assign the ordering by hour_count:
6 , y as (select date_page_requested
7 , hour_count
8 , row_number() over (order by hour_count desc, date_page_requested asc) as rn
9 from x)
And finally select the earliest row that has the greatest number of following rows.
10 select to_char(date_page_requested, 'YYYY-MM-DD HH24:Mi:SS')
11 , hour_count
12 from y
13* where rn = 1
If multiple 60 minute windows tie in hour count, the above will only give you the first window.
This should give you what you need, the first row returned should have
the hour with the highest number of pages.
select number_of_pages
,hour_requested
from (select to_char(date_page_requested,'dd/mm/yyyy hh') hour_requested
,count(*) number_of_pages
from pages
group by to_char(date_page_requested,'dd/mm/yyyy hh')) p
order by number_of_pages
How about something like this?
SELECT TOP 1
ranges.date_start,
COUNT(data.page) AS Tally
FROM (SELECT DISTINCT
date_page_requested AS date_start,
DATEADD(HOUR,1,date_page_requested) AS date_end
FROM #Table) ranges
JOIN #Table data
ON data.date_page_requested >= ranges.date_start
AND data.date_page_requested < ranges.date_end
GROUP BY ranges.date_start
ORDER BY Tally DESC
For PostgreSQL, I'd first probably write something like this for a "window" aligned on the minute. You don't need OLAP windowing functions for this.
select w.ts,
date_trunc('minute', w.ts) as hour_start,
date_trunc('minute', w.ts) + interval '1' hour as hour_end,
(select count(*)
from weblog
where ts between date_trunc('minute', w.ts) and
(date_trunc('minute', w.ts) + interval '1' hour) ) as num_pages
from weblog w
group by ts, hour_start, hour_end
order by num_pages desc
Oracle also has a trunc() function, but I'm not sure of the format. I'll either look it up in a minute, or leave to see a friend's burlesque show.
WITH ranges AS
( SELECT
date_page_requested AS StartDate,
date_page_requested + (1/24) AS EndDate,
ROWNUMBER() OVER(ORDER BY date_page_requested) AS RowNo
FROM
#Table
)
SELECT
a.StartDate AS StartDate,
MAX(b.RowNo) - a.RowNo + 1 AS Tally
FROM
ranges a
JOIN
ranges b
ON a.StartDate <= b.StartDate
AND b.StartDate < a.EndDate
GROUP BY a.StartDate
, a.RowNo
ORDER BY Tally DESC
or:
WITH ranges AS
( SELECT
date_page_requested AS StartDate,
date_page_requested + (1/24) AS EndDate,
ROWNUMBER() OVER(ORDER BY date_page_requested) AS RowNo
FROM
#Table
)
SELECT
a.StartDate AS StartDate,
( SELECT MIN(b.RowNo) - a.RowNo
FROM ranges b
WHERE b.StartDate > a.EndDate
) AS Tally
FROM
ranges a
ORDER BY Tally DESC