I have spent days trying to figure this out to no avail, so hopefully someone can help me. I have a queried date set which contains several fields including a column of dates. What I want to do is create a new field in my query that tells what the Monday and Friday is for the week of that row's particular date.
So for example; if the date in one of my rows is "1/16/18",
the new field should indicate "1/15/18 - 1/19/18".
So basically I need to be able to extract the Monday date (1/15/18) and the Friday date (1/19/18) of the week of 1/16/18 and then concatenate the two with a dash ( - ) in between. I need to do this for every row.
How on earth do I do this? I've been struggling just to figure out how to find the Monday or Friday of the given date...
Assuming that your column is of type date, you can use trunc to get the first day of the week (monday) and then add 4 days to get the friday.
For example:
with yourTable(d) as (select sysdate from dual)
select trunc(d, 'iw'), trunc(d, 'iw') + 4
from yourTable
To format the date as a string in the needed format, you can use to_char; for example:
with yourTable(d) as (select sysdate from dual)
select to_char(trunc(d, 'iw'), 'dd/mm/yy') ||'-'|| to_char(trunc(d, 'iw') + 4, 'dd/mm/yy')
from yourTable
gives
15/01/2018-19/01/18
There may be a simpler, canonical Oracle method to this but you can still reduce it to a simple calculation on your own either way. I'm going to assume you're dealing with only dates falling Monday through Friday. If you do need to deal with weekend dates then you might have to be more explicit about which logical week they should be attached to.
<date> - (to_char(<date>, 'D') - 2) -- Monday
<date> + (6 - to_char(<date>, 'D')) -- Friday
In principle all you need to do is add/subtract the appropriate number of days based on the current day of week (from 1 - 7). There are some implicit casts going on in there and it would probably be wise to handle those better. You might also want to check into NLS settings to make sure you can rely on to_char() using Sunday as the first day of week.
https://docs.oracle.com/cd/B19306_01/server.102/b14200/sql_elements004.htm
You can also use the NEXT_DAY function, as in:
SELECT TRUNC(NEXT_DAY(SYSDATE, 'MON')) - INTERVAL '7' DAY AS PREV_MONDAY,
TRUNC(NEXT_DAY(SYSDATE, 'FRI')) AS NEXT_FRIDAY
FROM DUAL;
Note that using the above, on weekends the Monday will be the Monday preceding the current date, and the Friday will be the Friday following the current date, i.e. there will be 11 days between the two days.
You can also use
SELECT TRUNC(NEXT_DAY(SYSDATE, 'MON')) - INTERVAL '7' DAY AS PREV_MONDAY,
TRUNC(NEXT_DAY(SYSDATE, 'MON')) - INTERVAL '3' DAY AS NEXT_FRIDAY
FROM DUAL;
in which case the Monday and Friday will always be from the same week, but if SYSDATE is on a weekend the Monday and Friday returned will be from the PREVIOUS week.
Related
I'm trying to compare the week number of a started task with the week before the current one.
and to_char(t.plan_start_dttm, 'YYYY-IW') = to_char(sysdate-1, 'YYYY-IW')
So yesterday, it was working fine, I got all records of last week. But today, I get the ones of this week.
So apparently, my "sysdate -1 is not the right way to do it.
Thank you
yesterday, it was working fine, I got all records of last week.
Yesterday was Monday of this week; so subtracting one day would be Sunday of last week and truncating to the start of the week would be Monday of last week.
Today is Tuesday; so subtracting one day would be Monday of this week and then truncating to the start of the week would still be this week.
Instead, subtract an entire week's worth of days (7):
and t.plan_start_dttm >= TRUNC( sysdate - 7, 'IW')
and t_plan_start_dttm < TRUNC( sysdate, 'IW' )
and if you compare on a range then Oracle can use an index on the plan_start_dttm column; whereas if you use TO_CHAR or TRUNC on the column then the column index cannot be used and you would need a separate function-based index.
Subtract 7 days instead of 1. Or 1 week. I also prefer trunc():
trunc(t.plan_start_dttm, 'IW') = trunc(sysdate - interval '7' day, 'IW')
There is no need to convert to strings for this purpose.
I need to find first Sunday of the month. tried with next_day function which produced proper result, but if the first day of the month is a Sunday then it doesn't work.
select next_day(trunc(sysdate,'MM'),'sun') first_sun
from dual
select next_day(trunc(sysdate,'MM'),'sun') first_sun
from dual
I'm running the query with the date sysdate='2019-09-10' which shows the 2nd Sunday instead of the 1st Sunday.
Just go back a day after truncating, so you find the first Sunday after the last day of the previous month:
select next_day(trunc(sysdate,'MM') - 1,'sun') first_sun from dual;
FIRST_SUN
----------
2019-09-01
You happen to land on month when Sunday is also the first day in month,
NEXT_DAY uses later than date, therefore you will have to check from previous day for example
select next_day(trunc(sysdate,'MM')-1,'SUNDAY') first_sun from dual;
NEXT_DAY returns the date of the first weekday named by char that is later than the date date.
I have a query were i pull data between 2 dates using the following.
AND TRLRACT.trndte BETWEEN (TRUNC(sysdate -3) + 02.5/24) AND (TRUNC(sysdate) + 2.5/24)
is there any way to have it exclude Saturday and Sunday when pulling data
You can check for day of the week in several ways, for example with
to_char(trndte, 'Dy') not in ('Sat', 'Sun')
(ignoring issues of NLS language). However, your days seem to start and end at 2:30 am, is something at 2 am on a Monday actually considered to be "Sunday"? If so, you should test trndte - 2.5/24 instead of trndte itself.
Need help figuring out how to determine if the date is the same 'day' as today in teradata. IE, today 12/1/15 Tuesday, same day last year was actually 12/2/2014 Tuesday.
I tried using current_date - INTERVAL'1'Year but it returns 12/1/2014.
You can do this with a bit of math if you can convert your current date's "Day of the week" to a number, and the previous year's "Day of the week" to a number.
In order to do this in Teradata your best bet is to utilize the sys_calendar.calendar table. Specifically the day_of_week column. Although there are other ways to do it.
Furthermore, instead of using CURRENT_DATE - INTERVAL '1' YEAR, it's a good idea to use ADD_MONTHS(CURRENT_DATE, -12) since INTERVAL arithmetic will fail on 2012-02-29 and other Feb 29th leap year dates.
So, putting it together you get what you need with:
SELECT
ADD_MONTHS(CURRENT_DATE, -12)
+
(
(SELECT day_of_week FROM sys_calendar.calendar WHERE calendar_date = CURRENT_DATE)
-
(SELECT day_of_week FROM sys_calendar.calendar WHERE calendar_date = ADD_MONTHS(CURRENT_DATE, -12))
)
This is basically saying: Take the current dates day of week number (3) and subtract from it last years day of week number (2) to get 1. Add that to last year's date and you'll have the same day of the week as current date.
I tested this for all dates between 01/01/2010 and CURRENT_DATE and it worked as expected.
Why don't you simply subtract 52 weeks?
current_date - 364
The SQL below will get you to the abbreviated name for the day of week, it's cumbersome but it works across versions of Teradata.
SELECT CAST(CAST(ADD_MONTHS(CURRENT_DATE, -12) AS DATE FORMAT 'E3') AS CHAR(3)) AS LY_DayOfWeek
, CAST(CAST(CURRENT_DATE) AS DATE FORMAT 'E3') AS CHAR(3)) AS CY_DayOfWeek
Dates are internally represented at integers in Teradata as (Year-1900) * 100000 + (MONTH * 100) + DAY. You may be able to do some creative arithmetic to figure out that 12/1/2015 Tuesday was 12/2/2014 Tuesday last year.
Normally I only show a record, if the actual date is one year later than the date in the database. How can I check if that day is a friday and then show also the records with the date of the saturday or sunday?
For example: Friday the 13th before one year. I will also show records from 14th(saturday) and 15th(sunday)
where myDate.arrival < TRUNC (SYSDATE) -365)
That's my actual statement.
You need a condition in case. Check the example below for reference:
WHERE txnday in
CASE to_char(sysdate, 'Day')
WHEN 'Friday' THEN // Include condition for Sat and Sun as well
ELSE // Include condition for only that day
END
Where Mydate.Arrival < Trunc (Sysdate) - 365
Or (to_char(Mydate.Arrival, 'D') = 6 AND Mydate.Arrival < Trunc (Sysdate) -363)
This way, you can check if that day is a Friday (6th day of week) and then select records whose Arrival value is less than sysdate - 363 (2 more days - Saturday and Sunday - included).