I have two columns, say "2010-10-26" and "2010-08-23" and I would like to obtain the interval in days, what is the best way to do this on a select query taking into account that there are months with 30,31,29,28 days? Is there any function that already does this?
Thank you.
If they are already in the date format, it's very easy:
SELECT '10/26/2010'::date - '08/23/2010'::date;
OR:
SELECT date '2001-10-01' - date '2001-09-28'; // outputs integer 3
Related
I found a weird thing. If a timestamp value subtract another, then Redshift will return an strange prefix. For example,
select table1.c_timestamp - table1.c_timestamp from table_1
Expect result should be ZERO or similar something, because these two timestamp values are same.
However, what I received is "5012369 years 4 mons", which I have no idea how does Redshift calculate the result.
Is there anyone can show me some clues?
Thanks
Contrary to the other answer,
Datediff doesn't exactly subtract, but rather counts the number of times the datepart chosen starts between the two timestamps.
datediff(second, '2018-04-10 00:00:00.001','2018-04-10 00:00:00.999')
>> 0
select datediff(second, '2018-04-10 00:00:00.999','2018-04-10 00:00:01.001')
>> 1
See: Datediff documentation
Edit: this is the way I found of how to perform the OP's task
SELECT
round(((EXTRACT('epoch' FROM TIMESTAMP '2018-05-27 09:59:59.999') - EXTRACT('epoch' FROM TIMESTAMP '2018-05-27 09:59:59.001'))*1000 + EXTRACT(millisecond FROM TIMESTAMP '2018-05-27 09:59:59.999') - EXTRACT(millisecond FROM TIMESTAMP '2018-05-27 09:59:59.001'))::real/1000)
The right way to subtract between datetimes is:
select datediff(seconds, table1.c_timestamp, table1.c_timestamp) from table_1
Of course, it doesn't make much sense to subtract a timestamp from itself, because that obviously returns 0, but I assume you just run that as a test.
I am trying to set up an dynamic threshold by different user, but only return result from today's date. I was able to return all the records from past 30 days, but I am having trouble only outputting today's date based on the calculation from past 30 days.. I am new to q language and really having a trouble with this simple statement :( (have tried and/or statement but not executing..) Thank you for all the help in advance!
select user, date, real*110 from table where date >= .z.D - 30, real> (3*(dev;real) fby user)+((avg;real) fby user)
Are you saying that you want to determine if any of todays "real" values are greater than 3 sigma based on the past 30 days? If so (without knowing much about your table structure) I'm guessing you could use something like this:
q)t:t,update user:`user2,real+(.0,39#10.0) from t:([] date:.z.D-til 40;user:`user1;real:20.1,10.0+39?.1 .0 -.1);
q)sigma:{avg[y]+x*dev y};
q)select from t where date>=.z.D-30, ({(.z.D=x`date)&x[`real]>sigma[3]exec real from x where date<>.z.D};([]date;real)) fby user
date user real
---------------------
2016.03.21 user1 20.1
I have found similar help, but the issue was more complex, I am only good with the basics of SQL and am striking out here. I get a handful of columns a,b,c,startdate,enddate and i need to parse that data out into multiple rows depending on how many months are within the range.
Eg: a,b,c,1/1/2015, 3/15,2015 would become:
a,b,c,1/1/2015,value_here_doesnt_matter
a,b,c,2/1/2015,value_here_doesnt_matter
a,b,c,3/1/2015,value_here_doesnt_matter
Does not matter if the start date or end date is on a specific day, the only thing that matters is month and year. So if the range included any day in a given month, I'd want to output start days for each month in the range, with the 1st as a default day.
Could I have any advice on which direction to begin? I'm attempting generate_series, but am unsure if this is the right approach or how to make it work with keeping the data in the first few arbitrary columns consistent.
I think generate_series is the way to go. Without knowing what the rest of your data looks like, I would start with something like this:
select
a, b, c, generate_series(startdate, enddate, interval '1 month')::date
from
my_table
I'm trying to find the best way to subtract 1 year and also one month from the current date in a Hive query. Using the following, I don't believe it will take into account leap years or if the fact that months have different amounts of days so eventually the code will break. Any help would be greatly appreciated!
set my_date = from_unixtime(unix_timestamp()-365*60*60*24, 'yyyy-MM-dd');
set my_date = from_unixtime(unix_timestamp()-30*60*60*24, 'yyyy-MM-dd');
Thank!
-Rebecca
If you have date format like yyyy-MM-dd hh:mm:ss in Hive, it is easy to implement using following functions
concat((year(date_field)-1),'-', (month(date_field)-1), '-', day(date_field))
Use IF and CASE functions to implement your logic to find whether it is a leap year or not(by dividing year by 4)
Background
Postgresql has the nice function date_trunc() which makes it easy to compute the date a week starts. This is great for aggregations on a week level. eg.
SELECT
date_trunc('week', create_date),
count(*)
FROM ...
GROUP BY 1;
HiveQL has the function WEEKOFYEAR() that gives you the week number. If you combine this with YEAR() you can make aggregates of the same type as in postgres.
SELECT
YEAR(create_date),
WEEKOFYEAR(create_date),
count(*)
FROM ...
GROUP BY YEAR(create_date), WEEKOFYEAR(create_date);
This is great. But what if I would like the actual date of the week?
Question
How can I compute the week date in HiveQL, from either a year and week number or directly from a timestamp?
Well there are not many functions in Hive. So it has the support for Custom UDF. You write your own function and integrate in Hive.
Here are some of the UDF which might be helpful:
1.) Link 1
2.) Link 2
Hope this helps..!!!