days into completed weeks only

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days into completed weeks only

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LoosinMaMind

Posted Monday, September 10, 2012 5:43 AM

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Hi

how do i easilty convert days into weeks (obviously Days/7 will give me weeks as decimal)

Problem i have is I only want to count completed weeks:

ie: 20 days is 2.86 weeks.

need answer to be 2 and not 3 as i get in SQL.

Thanks

Post #1356671

bitbucket-25253

Posted Monday, September 10, 2012 7:14 AM

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Is this what you need to do ?

SELECT 2.86 /1 - 2.86 % 1

                   SELECT 2.16 /1 - 2.16 % 1

Result for both selects is 2.000000

Note that the "%" is the modulo operator - check it out in BOL it is a powerful tool to become familiar with.

If everything seems to be going well, you have obviously overlooked something.

Ron

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Post #1356711

LoosinMaMind

Posted Monday, September 10, 2012 7:36 AM

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Thanks, sorted the issue now.

Post #1356729

davidandrews13

Posted Monday, September 10, 2012 7:38 AM

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i do:

select FLOOR(2.86)

Post #1356731

CapnHector

Posted Monday, September 10, 2012 7:47 AM

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LoosinMaMind (9/10/2012)

watch your data types. using integers 20/7 = 2 since SQL Server throws away the remainder when performing integer math. if you want to be absolutely certain / more precise / more explicit, i would use float or decimal with FLOOR().

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Post #1356739

Lynn Pettis

Posted Monday, September 10, 2012 8:04 AM

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LoosinMaMind (9/10/2012)

Thanks, sorted the issue now.

Proper forum etiquette would have you share your solution with others. It may help someone with a similar issue.

Cool

Lynn Pettis

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Post #1356755

CELKO

Posted Tuesday, September 11, 2012 7:22 AM

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Build a calendar table with one column for the calendar data and other columns to show whatever your business needs in the way of temporal information. Since SQL is a database language, we prefer to do look ups and not calculations. I would build a calendar table with a ISO-8601 weekday-within-year format column in addition to the usual Common Era date. This format is 'yyyyWww-d' where yyyy is the year, W is as separator token, ww is (01-53) week number and d is (1-7) day of the week.

Put a computed column for the week:

week_within_year COMPUTED AS SUBSTRING (weekday_within_year, 1, 7)

Now the query is a simple group by:

SELECT ..
FROM Calendar AS C, Foobar AS F
WHERE F.foo_date = C.cal_date
GROUP BY C.week_within_year
HAVING COUNT(*) = 7;

There are several websites with calendars you can cut & paste, but you can start your search with: http://www.calendar-365.com/week-number.html

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 #1357388

Mitesh Oswal

Posted Tuesday, September 11, 2012 7:54 AM

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Please check if this can help you!!!
select CAST(20.0/7 AS INT) + CASE WHEN (20%7) > 3 THEN 1 ELSE 0 END

Post #1357426

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