get the first date and weekday of every month in a year

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get the first date and weekday of every month in a year

vamsikrishnacheruku

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Points: 224
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March 10, 2014 at 11:42 am

#289221

hai i want to get the first date and weekday of every month in a year .
1/jan/2014, monday
1/feb/2014,thrusday
, ,
,,
,,
,,,
,,,
,,
1/nov/2014, thrusday
1/dec/2014, friday
like this output should be

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Wildcat SSCarpal Tunnel Points: 4774 More actions · Answer 1

--First Day of this Month

select DATEADD(mm, DATEDIFF(mm,0,getdate()), 0)

vamsikrishnacheruku (3/10/2014)
hai i want to get the first date and weekday of every month in a year .
1/jan/2014, monday
1/feb/2014,thrusday
, ,
,,
,,
,,,
,,,
,,
1/nov/2014, thrusday
1/dec/2014, friday
like this output should be

Luis Cazares SSC Guru Points: 183698 More actions · Answer 2

The best option could be a calendar table that can establish those values without further calculations.

If you don't have it, or can't create it, here's a possible option. Be sure to understand it and ask any questions you have before implementing it. It uses a Tally (or numbers) table in the form of a CTE. Understanding this concepts might help a lot (for this problem and many others).

DECLARE @Yearchar(4) = '2014';

WITH E1 AS(

SELECT N FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) E(N)

),

E3 AS(

SELECT a.N FROM E1 a, E1 b, E1 c

),

cteTally AS(

SELECT TOP (360) DATEADD( dd, (ROW_NUMBER() OVER( ORDER BY (SELECT NULL)) - 1), CAST(@Year AS date)) myDate

FROM E3

),

weekDays AS(

SELECT myDate, ROW_NUMBER() OVER(PARTITION BY MONTH(myDate) ORDER BY myDate) rn

FROM cteTally

WHERE DATENAME( WEEKDAY, myDate) NOT IN ('Saturday', 'Sunday')

)

SELECT myDate FirstWeekDay,

DATEADD(MM, DATEDIFF(MM, 0, myDate), 0) FirstDay

FROM weekDays

WHERE rn = 1

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

How to post data/code on a forum to get the best help: Option 1 / Option 2

Dwain Camps SSC Guru Points: 86908 More actions · Answer 3

There's an example in here: Calendar Tables in T-SQL[/url] that shows how to calculate the last work day of the month ("pay day"), which is not too dissimilar to your problem.

My mantra: No loops! No CURSORs! No RBAR! Hoo-uh![/I]
My thought question: Have you ever been told that your query runs too fast?

My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.

Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
[url url=http://www.sqlservercentral.com/articles/St

ScottPletcher SSC Guru Points: 100942 More actions · Answer 4

Not a big deal in this case, but I don't like generating hundreds of values when I need only 12 :-). I think code below does less work and also has no language dependencies:

DECLARE @year datetime

SET @year = GETDATE()

;WITH

cteDigits AS (

SELECT 0 AS digit UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL

SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9

),

cteMonths AS (

SELECT [10s].digit * 10 + [1s].digit AS month#

FROM cteDigits [1s]

CROSS JOIN cteDigits [10s]

WHERE

[10s].digit * 10 + [1s].digit BETWEEN 1 AND 12

)

SELECT

first_day_of_month +

CASE WHEN DATEDIFF(DAY, 0, first_day_of_month) % 7 < 5 THEN 0

WHEN DATEDIFF(DAY, 0, first_day_of_month) % 7 = 5 THEN 2 ELSE 1 END

AS first_workday_of_month

FROM cteMonths

CROSS APPLY (

SELECT DATEADD(YEAR, DATEDIFF(YEAR, 0, @year), 0) AS first_day_of_year

) AS ca1

CROSS APPLY (

SELECT DATEADD(MONTH, month# - 1, first_day_of_year) AS first_day_of_month

) AS ca2

ORDER BY

first_workday_of_month

SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.

Jeff Moden SSC Guru Points: 1003851 More actions · Answer 5

I originally missed what Scott was talking about and had to edit this post. Like he said, no biggee on this one but I agree... seems like there's a lot of rows being generated to support this task.

Shifting gears, I know the OP only asked for 1 year but I'd also write it to handle more than one year so I wouldn't have to run the code more than once.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Jeff Moden SSC Guru Points: 1003851 More actions · Answer 6

@scott,

I really like this line of clever code...

WHEN DATEDIFF(DAY, 0, first_day_of_month) % 7 = 5 THEN 2 ELSE 1 END

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 7

vamsikrishnacheruku (3/10/2014)
hai i want to get the first date and weekday of every month in a year .
1/jan/2014, monday
1/feb/2014,thrusday
, ,
,,
,,
,,,
,,,
,,
1/nov/2014, thrusday
1/dec/2014, friday
like this output should be

Can someone explain to me the weekdays? From what is posted above, it doesn't make any sense.

I ask because if you want the First of each month and the day it falls on, I cam up with this. Sorry Jeff, only coded it for a single year.

declare @Year date = getdate();

with TwelveCount(n) as (select n from (values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12))dt(n))

select

dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0)) FirstOfMonth,

datename(dw,dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))) NameOfDay

from

TwelveCount

order by

dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))

ScottPletcher SSC Guru Points: 100942 More actions · Answer 8

Lynn Pettis (3/14/2014)
vamsikrishnacheruku (3/10/2014)
hai i want to get the first date and weekday of every month in a year .
1/jan/2014, monday
1/feb/2014,thrusday
, ,
,,
,,
,,,
,,,
,,
1/nov/2014, thrusday
1/dec/2014, friday
like this output should be
Can someone explain to me the weekdays? From what is posted above, it doesn't make any sense.
I ask because if you want the First of each month and the day it falls on, I cam up with this. Sorry Jeff, only coded it for a single year.
declare @Year date = getdate();
with TwelveCount(n) as (select n from (values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12))dt(n))
select
dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0)) FirstOfMonth,
datename(dw,dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))) NameOfDay
from
TwelveCount
order by
dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))

I took it as meaning the first day of the month that does not fall on a Saturday or a Sunday, i.e., that is a "weekday", not a weekend-day.

SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 9

ScottPletcher (3/14/2014)
Lynn Pettis (3/14/2014)
vamsikrishnacheruku (3/10/2014)
hai i want to get the first date and weekday of every month in a year .
1/jan/2014, monday
1/feb/2014,thrusday
, ,
,,
,,
,,,
,,,
,,
1/nov/2014, thrusday
1/dec/2014, friday
like this output should be
Can someone explain to me the weekdays? From what is posted above, it doesn't make any sense.
I ask because if you want the First of each month and the day it falls on, I cam up with this. Sorry Jeff, only coded it for a single year.
declare @Year date = getdate();
with TwelveCount(n) as (select n from (values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12))dt(n))
select
dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0)) FirstOfMonth,
datename(dw,dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))) NameOfDay
from
TwelveCount
order by
dateadd(month,n - 1, dateadd(year,datediff(year,0,@Year),0))
I took it as meaning the first day of the month that does not fall on a Saturday or a Sunday, i.e., that is a "weekday", not a weekend-day.

Okay, but 2014-01-01 falls on a Wednesday so how do you get Monday?