Calulate number of days between datetimes [closed] - matlab

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I am trying to calculate the number of days between two datetimes in MATLAB.
startDate = datetime('12-Nov-2014 00:00:00','InputFormat','dd-MMM-yyyy HH:mm:ss')
endDate = datetime('18-Feb-2016 00:00:00','InputFormat','dd-MMM-yyyy HH:mm:ss')
Using diff I get the following result:
diff([startDate endDate])
ans =
11112:00:00
I am expecting a value of about 500 days not 11000.

If you can avoid to use datetime:
startDate = datenum('12-Nov-2014 00:00:00');
endDate = datenum('18-Feb-2016 00:00:00');
days = endDate-startDate
days =
463

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Converting SAS IFN(), HOUR() and MINUTE() to PostgreSQL [closed]

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(hour(date_column ) * 4)
+ ifn(minute(date_column ) = 0, 0
, ifn(minute(date_column ) <= 15, 1
, ifn(minute(date_column ) <= 30, 2
, ifn(minute(date_column ) <= 45, 3, 4))))
as date_no
What are the equivalents of these functions in PostgreSQL?
I am trying to extract value based on 15 mins interval in an hour.
It would help if you explained your goal and current logic in a bit more detail, but for now it looks like this would suffice:
select extract('hours' from date_column) * 4
+ ceil(extract('minutes' from date_column) / 15) as date_no
from your_table;
extract() is used in PostgreSQL for the same thing hour() and minute() are in SAS.
You can use CASE the exact same way you would in SAS but there's no IFN() counterpart.
CEIL() works the same in both, so you could also shorten your SAS version replacing all the IFN's.
You're effectively binning date/times, so you could look into date_bin(). Similar effect can probably be achieved in SAS through the use of INTNX() or plain ROUND() (1, 2).
Demo

How to convert '02-3月 -21' to date 21-03-02 00:00:00 psql [closed]

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How to convert '02-3月 -21' to date 21-03-02 00:00:00? in postgresql or kettle
I think a simple replace can do the trick here. Just replace the Chinese character 月 with nothing and format it.
SELECT TO_TIMESTAMP(REPLACE ('02-3月-21', '月', ''),'DD-MM-YY');
// output: 2021-03-02 00:00:00+00
SELECT TO_CHAR(TO_TIMESTAMP(REPLACE ('02-3月-21', '月', ''),'DD-MM-YY'), 'YY-MM-DD HH24:MI:SS')
// output: 21-03-02 00:00:00

Postgres Select all Sundays in 2019 [closed]

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how would I go about selecting data from only Sundays in 2019 in Postgres?
I think Sundays are a 0 but I am unsure as to how to query it like that.
I am selecting from a preexisting table that contains timestamp strings like 2020-09-03 02:11:60, so basically I want to select all the timestamps that occurred in 2019 in my table usermetrics in the column timestamp.
You have two requests.
The first to find timestamps in 2019:
SELECT
*
FROM
usermetrics
WHERE
timestamp BETWEEN '01/01/2019'::date AND '01/01/2020'::date
The second to find those that occurred on Sundays:
SELECT
*
FROM
usermetrics
WHERE
timestamp BETWEEN '01/01/2019'::date AND '01/01/2020'::date
AND
extract(DOW FROM timestamp) = 0;
01/01/2020::date is used as 12/31/2019::date would miss timestamps that occurred after midnight.

conversion from NSTimeInterval to days [closed]

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I have a date1 and the current Date when the view did load.
Now I want to display how many days have passed since the day.
let timeInterval = date1.timeIntervalSince(date2)
Now I want to convert the timeInterval in days.
Anyone could help?
Rather than using TimeInterval you can get the number of days directly by using the Calendar class and DateComponents
let days = Calendar.current.dateComponents([.day], from: date1, to: date2)
print(days.day!)

Syntax error while comparing timestamps in PostgreSQL [closed]

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Error: "syntax error at or near interval"
Join in question:
... LEFT OUTER JOIN usersession e ON a.userID = e.userID AND e.lastAction >= now() interval '-4h' * 1"
lastAction was created as lastAction timestamp NULL DEFAULT NULL
The idea is, to return some nils if the session's timestamp is 4 hours older than the current time.
No idea what the deal is here, never had to compare timestamps before either.
If you want records for the last 4 hours you need:
now() - interval '4 hours'
instead of
now() interval '-4h' * 1