Calculate weekend

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Calculate weekend

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kapil_kk

Posted Saturday, December 01, 2012 7:47 PM

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Hi,
I have a scenario in which i need to create a function which takes 2 parameter (count,startdate).
If I have a count of 30 and start date is 1/1/2012 then 30 should get added to atsrt date and it will return 31/1/2012.
No i need to caculate no. of sundays between 1/1/2012 and 31/1/2012. Suppose i have 4 sundays then i need to add 4in date 31/1/2012 which will result in 4/2/2012 , now again i have to calcualte that is there any sunday between 31/1/2012 and 4/2/2012 and so on.........
plz help me on this...

Post #1391686

robert.gerald.taylor

Posted Saturday, December 01, 2012 9:06 PM

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Take a look at this article by Lynn Pettis to see if that helps: http://www.sqlservercentral.com/blogs/lynnpettis/2009/03/25/some-common-date-routines/

Rob

Post #1391692

CELKO

Posted Saturday, December 01, 2012 9:13 PM

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I have a scenario in which I need to create a function which takes 2 parameter (displacement_count, start_date). If I have a count of 30 and start date is 2012-01-01 then 30 should get added to start_date and it will return 2012-01-31.

Please learn to use the ISO-8601 date formats; it is the only one allowed in Standard SQL and the other ISO Standards. Use the DATEADD() function for this.

Now I need to calculate the count of Sundays between 2012-01-01 and 2012-01-31. Suppose I have 4 Sundays then I need to add 4 in date 2012-01-31 which will result in 2012-02-04, now again i have to calculate that is there any Sunday between 2012-01-31 and 2012-02-04

SQL is a database language, so we use tables. The one you need for problem a calendar table with a Julianized date number. Here is a version that counts business days, change it for your purposes.

CREATE TABLE Calendar
(cal_date DATE NOT NULL PRIMARY KEY,
julian_business_nbr INTEGER NOT NULL,
...);

INSERT INTO Calendar
VALUES ('2007-04-05', 42),
('2007-04-06', 43), -- good Friday
('2007-04-07', 43),
('2007-04-08', 43), -- Easter Sunday
('2007-04-09', 44),
('2007-04-10', 45); --Tuesday

To compute the business days from Thursday of this week to next
Tuesdays:

SELECT (C2.julian_business_nbr - C1.julian_business_nbr)
FROM Calendar AS C1, Calendar AS C2
WHERE C1.cal_date = '2007-04-05',
AND C2.cal_date = '2007-04-10';

Books in Celko Series for Morgan-Kaufmann Publishing
Analytics and OLAP in SQL
Data and Databases: Concepts in Practice
Data, Measurements and Standards in SQL
SQL for Smarties
SQL Programming Style
SQL Puzzles and Answers
Thinking in Sets
Trees and Hierarchies in SQL

Post #1391693

Lynn Pettis

Posted Saturday, December 01, 2012 9:14 PM

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I'm not quite sure what you are asking for here. Are you trying to add 30 days to a given date such that you get a date x days later but skips Saturdays/Sundays?

Cool

Lynn Pettis

For better assistance in answering your questions, click here
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Post #1391694

Lynn Pettis

Posted Saturday, December 01, 2012 9:30 PM

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Based on the original post, I'm thinking you want something like this:


declare @TestDate date = '20120101',
        @DaysToAdd int = 8;

select
    @TestDate,
    @DaysToAdd,
    dateadd(dd, @DaysToAdd, @TestDate),
    datepart(wk,dateadd(dd, @DaysToAdd, @TestDate)),
    dateadd(dd, datepart(wk,dateadd(dd, @DaysToAdd, @TestDate)) - 1, dateadd(dd, @DaysToAdd, @TestDate));

Lynn Pettis

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #1391696

kapil_kk

Posted Sunday, December 02, 2012 7:46 AM

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yes you are right, I am trying to add 30 to a given date to get a x later date and want to count sunday in that date range and thn again add count of those sunday in that x date...

Post #1391723

kapil_kk

Posted Sunday, December 02, 2012 7:54 AM

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the script you have written is not satisfy the scenario that i wrote..

Post #1391724

Lynn Pettis

Posted Sunday, December 02, 2012 8:21 AM

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kapil_kk (12/2/2012)

the script you have written is not satisfy the scenario that i wrote..

You are going to have to tell me more than that it doesn't work. If I give it 2012-01-01 and 30 days, it returns 2012-02-04, just like you posted.

Maybe it doesn't satisify your actual requirements, but you really aren't giving us much to work with. We need the DDL (CREATE TABLE) statement for your table, some sample data as a seried of INSERT INTO statements, and the expected results based on the sample data. With that information you will get a better answer.

Cool

Lynn Pettis

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #1391728

Lynn Pettis

Posted Sunday, December 02, 2012 8:34 AM

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Lynn Pettis (12/2/2012)

kapil_kk (12/2/2012)

the script you have written is not satisfy the scenario that i wrote..

This appears to work if you stay in the same year:


declare @TestDate date = '20120201',
        @DaysToAdd int = 30;

select
    @TestDate,
    @DaysToAdd,
    dateadd(dd, @DaysToAdd, @TestDate),
    datepart(wk,dateadd(dd, @DaysToAdd, @TestDate)),
    datepart(wk,@TestDate),
    dateadd(dd, datepart(wk,dateadd(dd, @DaysToAdd, @TestDate)) - datepart(wk,@TestDate), dateadd(dd, @DaysToAdd, @TestDate));

Lynn Pettis

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #1391729

Lynn Pettis

Posted Sunday, December 02, 2012 8:40 AM

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As I think about this more, your apparent requirement is that everytime you cross Sunday you need to add an additional day, correct?

Example, if the startdate is 2012-11-30 (a Friday) and you add 3 days you would normally get 2012-12-03 (a Monday). What you want, however, is to get 2012-12-04 (a Tuesday). Is this correct?

Edit: And you probably want this to work over a year boundary as well, correct?

Cool

Lynn Pettis

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)

Post #1391730

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