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PostgreSQL, min, max and count of dates in range
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Closed 8 years ago.
I am getting min and max dates from text column with query which good people helped me to get there like this :
SELECT max(to_date(nullif(mydatetxt,''), 'DD.MM.YYYY')),
min(to_date(nullif(mydatetxt,''), 'DD.MM.YYYY'))
FROM table_name;
How can I get COUNT of all matched rows between and including min and max dates (written in text column)?
All you really need to do is:
SELECT count(*), max(to_date(nullif(mydatetxt,''), 'DD.MM.YYYY')), min(to_date(nullif(mydatetxt,''), 'DD.MM.YYYY'))
FROM table_name;
Or maybe I misunderstood. Really, you should, if at all possible, move the date field to a date type. If you have to handle garbage input, use a view and an update trigger to do that.
Related
Hive query equivalent of T-SQL Statement SELECT DATEADD(year, 1, '2019/05/25') ?
I am aware add_months() works for adding months to a given date. Now i am looking for adding years to a date.
Thanks
Try the functions years_add(timestamp date, int years) or years_sub(timestamp date, int years) which are mentioned in cloudera's latest documentation.
If this solutions doesn't work, you can still try using add_months() and multiply your desired number of years by 12 to add the correct number of months.
Hope this helps !
As you can see from the picture above I am trying to add new column and to calculate the difference between =2014-2017.
Is there any way to make this because Tableau's option "Table Calculation" doesn't play role for me.
Working out the difference between the first and last periods with table calculations:
First you need to get minimum year's values (i'm calling the field "Min Year Select"):
IF DATETRUNC('year',[Order Date]) =
{FIXED: MIN(DATETRUNC('year',[Order Date]))}
THEN 1 END
The above field named Min Year Select is saying that it should return a 1 if the year of the order date is the minimum year in your date range
Now we are flagging the smallest years, we can create a field to get the values (i'll call this "Min Year Segment"):
IF SUM([Min Year Select]) >= 1 THEN [Sales] END
Here we're saying that if the year is flagged as the smallest (as classified by the previous calc field we made), then get the value
But before we can compare the two values, you have to work out the number of time periods between the min and current year so that the difference calculation lookup field is comparing the right values (i'll call this "Number Years in Range"):
{FIXED [Segment]: COUNTD(DATETRUNC('year',[Order Date]))}
What we're doing is fixing the query at the category level (segment), think of this as removing the date pill from your report, then performing a calculation. Here it's COUNT DISTINCT years. So if a segment has data for 2011,2012,2013; then the query returns 3
We can now get the difference between your latest and your minimum Segments (called: "Difference from First Last Segment"):
[Segment] -
LOOKUP([Min Year Segment],
-1*(Number Years in Range)-1)
Firstly we get the first year's sales for each segment (Min Year Segment will be null for all years that aren't the first, so we need to lookup the first by going backwards by the number of years in our range:
We do -1 * because we want the lookup to lookup backwards, then we add in ("Number Years in Range" - 1) because we want to lookup to the period that had the earliest data. We do minus one so we're excluding the current year/latest year in your dataset
This is a lot to digest, I think it's easier to present as a picture too:
Here we calculate the difference between the first and last month, with the value in the last month
If this helped or you have any more questions, please vote on my answer/let me know
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.
How would i write a statement that would make specific group by's looking at the monthly date range/difference. Example:
org_group | date | second_group_by
A 30.10.2013 1
A 29.11.2013 1
A 31.12.2013 1
A 30.01.2015 2
A 27.02.2015 2
A 31.03.2015 2
A 30.04.2015 2
as long es there isnt a monthly date_diff > 1 it should be in the same second_group_by. I hope its clear enough for you to understand, the column second_group_by should be generated by the user...it doesnt exists in the table.
date diff between which rows though?
If you just want to separate years (or months or weeks) use
GROUP BY DATEPART(....)
That's Sybase or SQL Server but other SQLs will have equivalent.
If you have specific data ranges, get them into a table with start and end date-time and a monotonically increasing integer, join to that with a BETWEEN and GROUP BY the integer.
I apologise if this question has been asked but I cannot find an answer that quite fits.
I have a database with dates stored as 5 digit integers. I can covert these to datetime, however the dates are showing in the future.
For example,
select convert(datetime,StartDate,103)
from dpm.Schedule
where ScheduleID like 50003;
Gives the results of
2107-05-31 00:00:00:000 but this date should actually be 26/05/2008.
I am pretty new to T-SQL and have looked for sometime to find the answer to this but I am reaching the end of my sanity.
We cannot answer because you are doing a lot of confusion. To start 5003 is the Id of the record and [StartDate] is the value you are trying to convert.
Also drop using operator LIKE in the Id
Example:
select convert(datetime,50003,103)
returns:
2036-11-26 00:00:00.000
but you are trying to convert the value returned by
select StartDate
from dpm.Schedule
where ScheduleID = 50003;
Please edit your question and show us a nice example using SQL Fiddle