I am converting an old query from Legacy SQL to Standard SQL and noticed my report was off. I've traced it back to Legacy SQL and Standard SQL returning different weeks based off of a UNIX millisecond timestamp.
I was under the impression the Legacy SQL query was correct, but however, I'm curious to know the difference. It's not across all weeks, but enough to throw my report off significantly.
Here's an example:
#legacySQL
SELECT WEEK(MSEC_TO_TIMESTAMP(1470631859000)) AS sign_up_week;
Output: 33
#standardSQL
SELECT EXTRACT(WEEK FROM TIMESTAMP_MILLIS(1470631859000));
Output: 32
I've viewed the following documentation on the Legacy SQL reference:
WEEK(<timestamp>)
Returns the week of a TIMESTAMP data type as an integer between 1 and 53, inclusively.
Weeks begin on Sunday, so if January 1 is on a day other than Sunday, week 1 has fewer than 7 days and the first Sunday of the year is the first day of week 2.
And from the Standard SQL reference:
WEEK(<WEEKDAY>): Returns the week number of the date in the range [0, 53]. Weeks begin on WEEKDAY. Dates prior to the first WEEKDAY of the year are in week 0. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
ISOWEEK: Returns the ISO 8601 week number of the date_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
How can I get my Standard SQL query to output the same week number as my Legacy SQL query? If not, which week number is correct? It does not appear I can get them to dovetail natively.
This is a bit subtle, but legacy and standard SQL handle weeks differently. In Legacy SQL:
Weeks begin on Sunday, so if January 1 is on a day other than Sunday, week 1 has fewer than 7 days and the first Sunday of the year is the first day of week 2.
In Standard SQL:
WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
So, in Legacy SQL the first Sunday is week 2. In Standard SQL, the first Sunday is week 1.
Related
select extract(week from current_date) is giving 16 but current ISO week is 17.
Is this a bug or am I doing something wrong? Last week it worked OK.
You might be looking for:
extract(isoweek from current_date)
As per the documentation:
WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
ISOWEEK: Returns the ISO 8601 week number of the date_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
I have two event tables with timestamped data: Registered, Signed_In.
Both have rows such as: original_timestamp, user_id
I am trying to find out users who haven't signed in within 30 days after registering. I have used the following query but I cannot add a WHERE clause to it.
I tried a query but I am getting hourly difference, whereas I wanted days difference which is unsupported in BigQuery.
SELECT Signed_In.user_id, TIMESTAMP_DIFF(Registered.original_timestamp, Signed_In.original_timestamp, HOUR) AS days_difference
FROM `test_db.Signed_In` signed_in
JOIN `test_db.Registered` registered
ON Signed_In.user_id = Registered.user_id
GROUP BY 1,2
ORDER BY 2 DESC
WHERE days_difference > '30'
I am getting two columns: user_id, days_difference but the days_difference shows hours and my WHERE clause is rejected when I use it.
You can try this below code-
Note: Using Ordinal Position for GROUP BY and ORDER BY is not a good practice. Its always safe and standard to use the column names directly.
SELECT Signed_In.user_id,
TIMESTAMP_DIFF(Registered.original_timestamp, Signed_In.original_timestamp, HOUR) AS days_difference
FROM `test_db.Signed_In` signed_in
JOIN `test_db.Registered` registered
ON Signed_In.user_id = Registered.user_id
WHERE DATE_DIFF(Registered.original_timestamp, Signed_In.original_timestamp, Day) > '30'
GROUP BY 1,2
ORDER BY 2 DESC
Just replace HOUR to DAY in your query:
SELECT Signed_In.user_id, TIMESTAMP_DIFF(Registered.original_timestamp, Signed_In.original_timestamp, DAY) AS days_difference
Correct values are:
MICROSECOND
MILLISECOND
SECOND
MINUTE
HOUR
DAYOFWEEK
DAY
DAYOFYEAR
WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
WEEK(<WEEKDAY>): Returns the week number of timestamp_expression in the range [0, 53]. Weeks begin on WEEKDAY. datetimes prior to the first WEEKDAY of the year are in week 0. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
ISOWEEK: Returns the ISO 8601 week number of the datetime_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
MONTH
QUARTER
YEAR
ISOYEAR: Returns the ISO 8601 week-numbering year, which is the Gregorian calendar year containing the Thursday of the week to which date_expression belongs.
DATE
DATETIME
TIME
Why when I run
select (EXTRACT(WEEK FROM current_date)::int )
The output is 6 - why?
Today is 2016-02-14 which is the 8th week since the start of this year.
Am I getting this result wrong?
I'm looking for a function which I give it date and it tells me what week of the year this date is.
The documentation is pretty clear on the calculation:
week
The number of the ISO 8601 week-numbering week of the year. By
definition, ISO weeks start on Mondays and the first week of a year
contains January 4 of that year. In other words, the first Thursday of
a year is in week 1 of that year.
In the ISO week-numbering system, it is possible for early-January
dates to be part of the 52nd or 53rd week of the previous year, and
for late-December dates to be part of the first week of the next year.
For example, 2005-01-01 is part of the 53rd week of year 2004, and
2006-01-01 is part of the 52nd week of year 2005, while 2012-12-31 is
part of the first week of 2013. It's recommended to use the isoyear
field together with week to get consistent results.
Weeks start on a Monday, so Sunday is the end of a week (and "today" is Sunday where I am and in most of the world at this particular time). Also, the first week depends on the when the year starts.
I need some help in writing an SQL in SQL Server where I need to count number of rows group by weeks. There is a tricky description of week which is following
- For any date before 08/13/2015 the week is of 7 days (i.e. from Thu through Wed)
- For date 08/13/2015 the week is consider a 9 day week (i.e. from Thursday through Friday so its between 08/13/2015 through 08/21/2015)
- For date 08/22/2015 the week is back to 7 days (i.e. Sat through Friday)
Now having said all the above the result I want to see in my report is the following way . NOTE: WE column in the below attached image is the last day of the week for the range.
Sample Result Image
Just write a case statement for the 3 different options. You can find the start day with something like this:
DATEADD(week, DATEDIFF(day, 3,getdate()) / 7, 3) -- Thursdays
DATEADD(week, DATEDIFF(day, 5,getdate()) / 7, 5) -- Saturdays
The numbers 3 and 5 come from the fact that day 0 (=1.1.1900) is Monday.
If you use this a lot, it might be a good idea to write a inline table valued function to return the dates you need.
I have two current SQL queries that I currently use to compare GM% from previous year vs. GM% this year. This is a daily report that I run every morning. The date arithmetic is not very solid and I am trying to find an alternative. Previously I thought that the report would only be for Monday forward, and not including the current day (ie if ran on Tuesday, it would only pull Monday. If ran on Monday it would not pull anything.) Recently that has changed to where when the report is ran on Monday, they want to see Friday-Sunday. What I am considering is setting it to pull the previous 5 day, not including the current day. (Ran on Monday would pull Thur, Fri, Sat, Sun.) The problem is that it has to be a day this year vs same day last year comparison. Anyone who;s tried this knows that it is not easy to get this. Here is my current code for the date arithmetic. I am at a loss guys, I could use some help.
Where DB1.TB1.CLM1>=Current Date-364 days - (DAYOFWEEK(CURRENT DATE) - 2) DAYS
And DB1.TB1.CLM1< Current Date- 364 days
If I hear you right, on Tuesday you would pull stats for Monday. Wed, you pull stats for Mon-Tues. Friday, you pull Mon-Thurs. And for all of these, you need the equivalent day prior year.
The trick is that now on Monday, you need to pull the previous weekend, i.e. Thu-Sun.
You have not defined what to do on Sunday, so I'm leaving that case out.
Try this WHERE statement:
where
( -- do this after Monday
dayofweek(current date) > 2 and
DB1.TB1.CLM1 between ((current date - 364 days) - (dayofweek(current date) - 2) days) and (current_date - 365 days)
)
or
( -- do this on Monday
dayofweek(current date) = 2 and
DB1.TB1.CLM1 between (current date - 368 days) and (current date - 365 days)
)