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Date comparison in sql server

Hello,

There are two date columns in the table.

I want to compare just the Month and Year portion between those two dates with also taking the Year into consideration.

Case 1:
For Eg
DateColumn1 = '01-OCT-2013'
DateColumn2 = '01-JAN-2014'

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When I compare the Month and year in DateColumn1 against DateColumn2, it should tell me that DateColumn1 is less (i.e, earlier) than DateColumn2, even though the Month October in DateColumn1 is a later month compare to Jan, theDatColumn1 is in the past year and DateColumn2 is in the current year.


Case 2:
DateColumn1 = '01-JAN-2014'
DateColumn2 = '02-JAN-2014'

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Here it should tell me that the difference is 0 as the month and the year match in this case.


Case 3:
DateColumn1 = '01-Aug-2014'
DateColumn2 = '02-JAN-2014'

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Here it should tell me that the DateColumn2 is lesser than DateColumn1.


How to accomplish this?

Thanks!
0
sath350163
Asked:
sath350163
4 Solutions
 
Pratima PharandeCommented:
Not sure in what format you want the answer .
As I understand you want to compare two dates and need result like which is less , or same depending on month and yesr

try this - hope it helps
Declare @date_col1 as datetime
declare @date_col2 as datetime

set @date_col1 = '01-Aug-2014'
set @date_col2 = '02-JAN-2014'

select
Case when datediff(month,@date_col1,@date_col2) < 0 then 'date col 2 is less'
when datediff(month,@date_col1,@date_col2) > 0 then 'date col 1 is less'
      
 else ' both equal ' end
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sath350163Author Commented:
Thanks for the response.

But I also want the year to be taken into consideration for decision on whether the date is lesser or greater.

Thanks!
0
 
PortletPaulfreelancerCommented:
DateDiff(month,[date_1],[date_2])

will take the year into account, what the 'month' is doing in that function is identifying the unit of precision (month), but it is still comparing full date values (i.e. they already include the year).

also see:
http://technet.microsoft.com/en-us/library/ms189794.aspx
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Pratima PharandeCommented:
Yes , Datediff function takes yesr in consideration . try out your inputs and check the results
as per yiur requirement
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ZberteocCommented:
I can give you an example for each of the cases using the DATEDIFF function that will return the difference in months between 2 dates.

1. If the number is positive means that the @DateColumn2 is bigger than @DateColumn1
2. If the number = 0 (0 months difference) means teh Year and Month are the same
3. If the number is negative means that @DateColumn1 is bigger than @DateColumn2

--declare variables
declare
	@DateColumn1 datetime,
	@DateColumn2 datetime

--case 3 returns 3 months difference, which means date2 > date1
select 
	@DateColumn1 ='01-OCT-2013',
	@DateColumn2 ='01-JAN-2014'

select DATEDIFF(mm, @DateColumn1,@DateColumn2) as diff

--case 2 returns 0 months difference, which means date1 Year&month = > date2 Year&month
select 
	@DateColumn1 ='01-JAN-2014',
	@DateColumn2 ='02-JAN-2014'

select DATEDIFF(mm, @DateColumn1,@DateColumn2) as diff

--case 3 returns -7 months difference, which means date1 > date2
select 
	@DateColumn1 ='01-Aug-2014',
	@DateColumn2 ='02-JAN-2014'

select DATEDIFF(mm, @DateColumn1,@DateColumn2) as diff


-- to use with columns

select DATEDIFF(mm, DateColumn1,DateColumn2) as diff from yourtable

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David ToddSenior DBACommented:
Hi,

I suggest that if you are only interested in the year/month, look at this:

select dateadd( month, datediff( month, 0, getdate()), 0 )

This will return (at present) 2014-02-01 00:00:00.0000

This is very similar code to that which removes the time from a datetime.

So, this works for years, quarters, months, days, hours, minutes - needs some adjusting for weeks, and for seconds.

HTH
  David
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