How to get the Initial date of the month in DB2 - stored-procedures

In StoredProcedure we are passing the date like 'From date' = 2014-08-12 and 'End Date' = 2015-06-24.
I want to find like 'From Date' = 2014-08-01 and 'End Date' =2015-06-30.

So you want to go from the beginning of whatever month is passed in as from, to the ending of whatever month is passed in as end.
Beginning of month
last_day(fromdate) + 1 day - 1 month
End of the month
last_day(enddate)
You might find it useful to create a user defined function that encapsulates the beginning of month logic.

--Beginning of month
FromDate - (day(FromDate) -1) days
--End of the month
LAST_DAY(EndDate)

To get the dates between the start and end of the current month:
where date between (current_date - (day(current_date) - 1) days) and (current_date + 1 month - (day(current_date)) days)
You will probably want to replace this current date with another date, or the minimum and maximum values from some other table or result.

Related

How to run Rails queries over multiple date ranges (weeks)

I'm trying to iterate over each week in the calendar year and run a query.
range = Date.new(2020,3,16)..Date.new(2020,3,22)
u = User.where(created_at: range).count
But I'd like to do this for EACH week in another range (say since the beginning of this year).
Ruby's Date has a cweek function that gives you the week number but there doesn't seem to be a way to easily get from the week number to the date range.
Anyway, not sure how helpful cweek will be as I need week to run Sunday -> Saturday.
Thoughts?
I'm assuming this is Postgres and the model name is User based on your previous question.
If this blog is to to believed you can shift a date one day to get sun-sat day week.
User.group("(date_trunc('week', created_at::date + 1)::date - 1)")
.count
If you want the to select the actual week number while you are at it you can select raw data from the database instead of using ActiveRecord::Calculations#count which is pretty limited.
class User
# #return [ActiveRecord::Result]
# the raw query results with the columns count, year, week
def self.count_by_biblical_week
connection.select_all(
select(
"count(*) as count",
"date_part('year', created_at)::integer as year",
"(date_part('week', created_at::date + 1) - 1)::integer as week"
).group(:week, :year)
)
end
end
Usage:
results = User.where(created_at: Date.new(2020,3,16)..Date.new(2020,3,22))
.count_by_biblical_week
results.each do |row|
puts [row[:year], row[:week], row[:count]].join(' | ')
end
Adding the year to the group avoids ambiguity if the results span multiple years.

How to add a number to the date ruby

I have method:
def date_of_next()
date = Date.parse('Monday')
delta = date > Date.today ? 0 : 7
date + delta
return date.strftime('%Y-%w-%d'), (date + 7).strftime('%Y-%w-%d')
end
This method specifies the date of Monday this week.
In return, I also return the date of Monday next week, but it does not display the date that needs to be
if I run this method in the .rb file then it prints everything well
2019-01-28
2019-02-4
but if run this method in rails controller, there is a problem with the date
2019-01-28
2019-01-04
As you see, there is a problem with the date of the month.
I do not understand what the problem is, help
I think you're going a little heavy on your code for a method that returns Monday this Week and Monday next week.
def beginning_of_weeks
monday = Date.new.beginning_of_week
return monday, monday + 7.days
end
You can, of course, add the formatting function strftime('%Y-%m-%d') inside the method, though it would be better organized somewhere else.
Maybe you mixed date format?
def date_of_next()
date = Date.parse('Monday')
delta = date > Date.today ? 0 : 7
date + delta
return date.strftime('%Y-%m-%d'), (date + 7).strftime('%Y-%m-%d')
end

Rails: Is there away to get the Date object that is the closest Monday to today?

Given a date, how do I find the nearest Monday in Rails?
I know I can do things like:
Date.tomorrow
Date.today
Is there something like Date.nearest :monday ?
The commercial method on the Date object will let you do this. This example will get you the next Monday.
Date.commercial(Date.today.year, 1+Date.today.cweek, 1)
If you need the next or previous Monday, whichever is closest, you can do:
Date.commercial(Date.today.year, Date.today.cwday.modulo(4)+Date.today.cweek, 1)
I can't execute this right now, so forgive me if there are syntax errors.
It's a little bit tricky, but not so hard to calculate.
Use ActiveSupport::DateAndTimeCalculations#end_of_week to calculate end of a week, this method accepts a start_day parameter that is used to indicate start day of the week (it's :monday by default). They even have implemented sunday method.
The trick is the following: if you want to calculate closest Monday, you may calculate it as a end of the week which starts on Tuesday (Tue => 1st day, Wed => 2nd day, ..., Mon => 7th day which is also end of the week).
So all you need to do is:
# it will return current date if today is Monday and nearest Monday otherwise
Date.today.end_of_week(:tuesday)
I know this is an old thread but it's always nice to keep it current for future seekers.
Let's assume today is say Friday the 19th of August. All I do to get my nearest Monday is this:
monday = Date.today.monday
Then from there you can go back a week or forward a week like this:
last_monday = monday.last_week
next_monday = monday.next_week
Assuming you want both directions: Date.today.beginning_of_week + 7*(Date.today.wday/5)
Untested, so you might need to finetune, but here you go:
def Date.nearest_monday
today = Date.today
wday = today.wday
if wday > 4 # over the half of the week
today + (7 - wday) # next monday
else
today - (1 + wday) # previous monday
end
end

How do I get a Date from a week number?

I want to find all items created in a given week, and pass in a week number param. (created_at is a normal timestamp.)
Given a week number, what is the easiest way to find a date in that particular week?
(Any date in the week will do, as I will use beginning_of_week and end_of_week in the scope.)
You can get Date objects representing the beginning and end of your week using the commercial method:
week = 41;
wkBegin = Date.commercial(2010, week, 1)
wkEnd = Date.commercial(2010, week, 7)
Now do your find:
Item.find(:all, :conditions->:create_date=>wkBegin..wkEnd.end_of_day)
Assuming you mean "a given week number in the current year", you can do the following:
2.weeks.since(Time.gm(Time.now.year))
=> Fri Jan 15 00:00:00 UTC 2010
Substitute (week_number - 1) for the 1 in the above, and you'll get a date in the desired week.

Groovy/Grails date class - getting day of month

Currently I'm using the following code to get year, month, day of month, hour and minute in Groovy:
Date now = new Date()
Integer year = now.year + 1900
Integer month = now.month + 1
Integer day = now.getAt(Calendar.DAY_OF_MONTH) // inconsistent!
Integer hour = now.hours
Integer minute = now.minutes
// Code that uses year, month, day, hour and minute goes here
Using getAt(Calendar.DAY_OF_MONTH) for the day of the month seems a bit inconsistent in this context. Is there any shorter way to obtain the day of the month?
If you add the following to your code it should assign the day of the month to the day Integer:
Integer day = now.date
Here's a stand-alone example:
def now = Date.parse("yyyy-MM-dd", "2009-09-15")
assert 15 == now.date
Isn't all those lines are kind of garbage?
The following two lines do the job in a groovysh
date = new Date()
date.getAt(Calendar.DAY_OF_MONTH)
To use this at your real code and not in the console
def date = new Date()
def dayOfMonth = date.getAt(Calendar.DAY_OF_MONTH)
The way you are doing it is the only way. The java date object stores the month and day, but doesn't store any information such as how long the given month is or what day of the month your on. You need to use the Calendar class to find out a lot of this info.
You can get just the day of the month from a Date in Groovy like this:
​Date date = new Date()
int dayOfMonth = date[Calendar.DAY_OF_MONTH]
This version is fairly terse:
Calendar.instance.get(Calendar.DAY_OF_MONTH)

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