How do I select in U-SQL Monday of this week and Monday of the week before?
Many thanks in advance!
Since the expression language in U-SQL is C#, you can use C# expressions. The following stackoverflow thread shows some examples:
Get the Monday and Sunday for a certain DateTime in C#
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I have the following azure function that is supposed to retrieve the date of the previous Monday. It works fine except for if the current date is a monday. I need the function to still retrieve the previous monday date if it is Monday or Tuesday. This is due to the time not being updated until middle of day tuesday.
#{formatDateTime( subtractFromTime( utcNow(), sub(dayOfWeek(utcNow()),1), 'Day' ), 'yyyy-MM-dd 00:00:00' )}
I am still learning Azure synapse so I am not sure if I can write an IF statement that accomplishes this or if there is a better way to write it.
I have reproduced the above and able to get the desired result by using the below dynamic content.
#if(greater(dayOfWeek(utcnow()),1),formatDateTime(addDays(subtractFromTime(utcnow(),dayOfWeek(utcnow()),'Day'),1),'yyyy/MM/dd'),formatDateTime(addDays(subtractFromTime(utcnow(),dayOfWeek(utcnow()),'Day'),-6),'yyyy/MM/dd'))
The day of week for a monday from last sunday is 1, so I am checking the current date's day of week is greater than monday or not.
If it is greater (Today is not a Monday), then I am giving last Monday by adding 1 day to the last Sunday.
If it is not, then I am subtracting -6 from the last Sunday which is the previous Monday.
This will work for all days, but we need to change the condition and the number which we are adding and subtracting as per the day we required.
Result:
If you want the result to be Monday even though current date is Monday or Tuesday, then give the expression for Tuesday also in the above condition using or.
I want to find out the previous weeks's last day in Teradata SQL using Sunday as the last day of the week. For example, today is Friday 1/27, so the last week ended on Sunday (1/22) and I would want to return 2023-01-22.
Other examples:
If current date is '2023-01-02', then the output I require is '2023-01-01'
If current date is '2023-01-18', then the output I require is '2023-01-15'
With Hive query I would use:
date_sub(current_date, cast(date_format(current_date, 'u') as int));
What would the equivalent be in Teradata? I've tried using the code below but it seems to return the date of the closest Sunday instead of the date of the previous Sunday.
SELECT ROUND(current_date, 'd') (FORMAT 'yyyy-mm-dd');
There are several ways:
Probably the best one is one of the built-in functions to return the previous xxxday <= the input date:
Td_Sunday(Current_Date - 1)
Or the function to return the next xxxday > input date:
Next_Day(Current_Date - 8, 'sun')
Truncating is least understandable:
Trunc(Current_Date, 'IW') -1
TRUNC supports three variations, only IW is usable, but restricted to Monday as week start:
IW: the Monday of the ISO week
WW: the same day of the week as January 1st of the year
W: the same day of the week as the first day of the month
You can use the trunc function to return the first day of the a week, month, ect.
select trunc(current_date -7 ,'IW')
Current date today is 2023-01-27. This will return 2023-01-15, the previous Sunday.
EDIT: Sorry, meant to use the ISO week. As Dnoeth points out, the regular week option doesn't work consistently (which I didn't know, never used it for this before). Anyhoo, his answer is better than mine...
I'm working with Big Query and I need to get first day of week.
For example if date = '2022-08-26' I want to have '2022-08-22' where 22 is Monday.
Any solutions please ?
Thanks in advance.
To achieve this you'll want to use the DATE_TRUNC function as follows:
select date_trunc(date('2022-08-26'), WEEK(MONDAY))
You can change the parameter for WEEK to be any day of the week, default is SUNDAY.
Documentation can be found here:
https://cloud.google.com/bigquery/docs/reference/standard-sql/date_functions#date_trunc
I need to convert Week to start with Sunday (range 1-53, with a Sunday in this year)
Ex. DATE_PART(w,'2020-01-05') (Sunday)
This should return 2 instead of 1.
Thanks in advance.
If you wish to obtain the Week Number where a week starts on Monday instead of Sunday:
Subtract one day to the date being convert to the Week Number
So, use:
DATE_PART(w, date_field - INTERVAL '1 DAY')
This returns the Week Number of the 'previous day'.
Unfortunately, it won't work for the first day of the year, which will appear to be the last day of the previous year. Depending on how your organization treats the first/last weeks of the year, this might be okay.
If that is not satisfactory, then you could write your own User-Defined Function (UDF) and code it to return the values you desire.
While answering Regexp matching ISO8601 date/time format I wondered how you express first coming Monday or repeat every monday in ISO8601.
My guess would be something like:
W-1
R/W-1
But I cannot find a confirmation of that.
ISO 8601 has the concept of week dates which allow you to specify a week of the year and the day of the year. In the following example 2014-W01-1 means the first week of 2014 on Monday. Then repeat that every week using P1W
R/2014-W01-1T00:00:00/P1W
Seen in this answer