Get last week and next week number from week number - sql

I would like to get last week and next week number from week number.
How to get the next week number if it's December or the last week if it's January ?
I use ISO week numbers.
Desired results:


select datepart(year,dateadd(day,-1,week_dt_start)) * 100 +
datepart(week,dateadd(day,-1,week_dt_start)) as prev_week,
datepart(year,dateadd(day,1,week_dt_end)) * 100 +
datepart(week,dateadd(day,1,week_dt_end)) as next_week
from tablename

Related

SQL week number for the whole table

How to create a new column which calculates week number but for the whole table ignoring year?
Desired output is as follows:
Appreciate any help :)

You can do this by calculating 1st day of week of oldest row, and then calculate day diff of 1st day of week of current row and coldest row, after that, divide it by 7 days plus 1 will give you the desired week number across the full table.
Assuming you are using MySQL and the first day of the week is Sunday:
WITH min_week_start AS (
SELECT
SUBDATE(MIN(record_date), dayofweek(MIN(record_date)) - 1) as week_start_date
FROM
record_table
),
record_week_start AS (
SELECT
record_date,
SUBDATE(record_date, dayofweek(record_date) - 1) as week_start_date
FROM
record_table
)
SELECT
record_week_start.record_date,
DATEDIFF(record_week_start.week_start_date, min_week_start.week_start_date) / 7 + 1 as week_num
FROM
record_week_start
CROSS JOIN
min_week_start

How to get the start date of the week by week number of year in Hive? First day of week should be Monday

I have a week number of year in ISO format and I want to get start date of this week in Hive. First date of week is Monday.
Example: year 2020 week 50 - start date should be 2020-12-07

Try the code below, where year and week are the corresponding column names of your table.
select date(
from_unixtime(
unix_timestamp(concat(year,'-',week,'-','1'), 'yyyy-w-u')
)
) from <your_table_name>;

VBA convert week and day to date

I have a table with week number and day of week.
Example:
J2 = 18
G2 = Monday
How can I convert this to 2018-04-30?
I can find lots of threads for converting the other way around, meaning date to week. But I can't find anything on week + weekday to date.
Anyone know of a method?

The (optional) second argument of the WEEKDAY function determines what the first day of the week is. The two most common choices are:
1: Sunday (1) to Saturday (7)
or
2: Monday (1) to Sunday (7)
But, you can start on Wednesday, Friday, etc if you want. Pick an option now.
So, start with 1st January (of whichever unspecified year you're working with), and subtract the weekday of 1st January, according to whichever start-day you picked. This gives you a baseline for Week 1. To get to the start of Week n, you just need to add 7*(n-1) days.
Finally, you need to add the weekday back on. I'm going to recommend using MATCH on an array. Your array will be your weekdays, in order, surrounded by curly brackets. So, for Sunday-to-Saturday, you would use
MATCH(G2,{"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"},0)
to get a number from 1 ("Sunday") to 7 ("Saturday"), or #NA if cell G2 does not contain a day-name.
Stick it all together, and you get something like this:
=DATE(YEAR(NOW()),1,1) - WEEKDAY(DATE(YEAR(NOW()),1,1),1) + 7*(J2-1) + MATCH(G2,{"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"},0)

Try this, necessary comments in code:
Option Explicit
Sub GetDate()
Dim year As Date, day As Long
'convert day in G2 to integer
Select Case Range("G2").Value
Case "Monday"
day = 1
Case "Tuesday"
day = 2
'rest of cases
End Select
'declare what year you want
year = "01-01-2018"
'move from first week to the week specified in J2
year = DateAdd("d", (Range("J2").Value - 1) * 7, year)
'move back to first day of the week
Do While DatePart("w", year, vbMonday) <> 1
year = DateAdd("w", -1, year)
Loop
'find date of particular day
Do While DatePart("w", year, vbMonday) <> day
year = DateAdd("w", 1, year)
Loop
End Sub

The determination depends critically on your definition of "week number".
If you are using the ISO-8601 definition, where a Week starts on Monday and week 1 contains the first Thursday of the year, you can use this worksheet formula:
=DATE(YEAR(TODAY()),1,-2)-WEEKDAY(DATE(YEAR(TODAY()),1,7),14)+$J$2*7+MATCH($G$2&"*",{"Monday";"Tuesday";"Wednesday";"Thursday";"Friday";"Saturday";"Sunday"},0)-1
you may need to change the commas to semicolons depending on your regional settings
To explain:
First, find the last Monday of the previous year:
DATE(YEAR(TODAY()),1,-2)-WEEKDAY(DATE(YEAR(TODAY()),1,7),14)
Then add seven(7) times the number of desired weeks:
+$J$2*7
Then add the number of days from Monday to the desired day for that week:
+MATCH($G$2&"*",{"Monday";"Tuesday";"Wednesday";"Thursday";"Friday";"Saturday";"Sunday"},0)-1

How to subtract 13 weeks from a date in PL SQL?

I have a date in sql which will always fall on a Monday and I'm subtracting 13 weeks to get a weekly report. I am trying to get the same 13 week report but for last year's figures as well.
At the moment, I'm using the following:
calendar_date >= TRUNC(sysdate) - 91
which is working fine.
I need the same for last year.
However, when I split this into calendar weeks, there will also be a partially complete week as it will include 1 or 2 days from the previous week. I need only whole weeks.
e.g. the dates that will be returned for last year will be 14-Feb-2015 to 16-May-2015. I need it to start on the Monday and be 16-Feb-2015. This will change each week as I am only interested in complete weeks...

I would do this:
Get the date by substracting 91 days as you're already doing.
Get the number of the day of the week with TO_CHAR(DATE,'d')
Add the number of days until the next monday to the date.
Something like this:
SELECT TO_DATE(TO_DATE('16/05/2015','DD/MM/YYYY'),'DD/MM/YYYY')-91 + MOD(7 - TO_NUMBER(TO_CHAR(TO_DATE(TO_DATE('16/05/2015','DD/MM/YYYY'),'DD/MM/RRRR')-91,'d'))+1,7) d
FROM dual

next_day - returns date of first weekday named by char.
with dates as (select to_date('16/05/2015','DD/MM/YYYY') d from dual)
select
trunc(next_day( trunc(d-91) - interval '1' second,'MONDAY'))
from dates;
I want to get next monday from calculated date. In situation when calculated date is monday i have to move back to previous week ( -1 second).

Adding relative week number column to MySQl results

I have a table with 3 columns: user, value, and date. The main query returns the values for a specific user based on a date range:
SELECT date, value FROM values
WHERE user = '$user' AND
date BETWEEN $start AND $end
What I would like is for the results to also have a column indicating the week number relative to the date range. So if the date range is 1/1/2010 - 1/20/2010, then any results from the first Sun - Sat of that range are week 1, the next Sun - Sat are week 2, etc. If the date range starts on a Saturday, then only results from that one day would be week 1. If the date range starts on Thursday but the first result is on the following Monday, it would be week 2, and there are no week 1 results.
Is this something fairly simple to add to the query? The only ideas I can come up with would be based on the week number for the year or the week number based on the results themselves (where in that second example above, the first result always gets week 1).
Example:
$start = "05/27/2010";
$end = "06/13/2010";
//Query
Result:
week date user value
1 05/28/2010 joe 123
3 06/07/2010 joe 123
3 06/08/2010 joe 123
4 06/13/2010 joe 123

This can easily be done with this simple and obvious expression :)
SELECT ...,
FLOOR(
(
DATEDIFF(date, $start) +
WEEKDAY($start + INTERVAL 1 DAY)
) / 7
) + 1 AS week_number;
Some explanation: this expression just calculates difference between the given date and the start date in days, then converts this number to weeks via FLOOR("difference in days" / 7) + 1. That's simple, but since this works only when $start is Sunday, we should add an offset for other week days: WEEKDAY($start + INTERVAL 1 DAY) which equals to 0 for Sun, 1 for Mon, ..., 6 for Sat.