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Calculating age based on month

Posted on 2014-10-17
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Last Modified: 2014-10-17
If I am calculating age based on "date" using this query

select * 
from tblregistrations
WHERE  YEAR('20140701') - YEAR(DOB)
        - ( CASE
               WHEN MONTH(DOB) > MONTH('20140701')
                 OR ( MONTH(DOB) = MONTH('20140701')
                    AND DAY(DOB) > DAY('20140701')
                    )
               THEN 1
               ELSE 0
             END )  < 18

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How can I calculate based on "month" only?  Thanks for helping this novice sql person.
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Question by:al4629740
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9 Comments
 
LVL 48

Expert Comment

by:PortletPaul
ID: 40387609
please provide an example of what you mean by "month only"

is the DOB "month only"?
are you still comparing to the constant '20140701'?
an example would really help
0
 

Author Comment

by:al4629740
ID: 40387621
No, the new constant will be the month

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LVL 69

Expert Comment

by:Scott Pletcher
ID: 40387631
If you want to see if a person is less than a certain age, you can just calculate the "controlling date", and then test for the DOB < that.  Something like this:

select *
from tblregistrations
WHERE  
    DOB < DATEADD(YEAR, -18, '20140701')
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Author Comment

by:al4629740
ID: 40387644
No, I just want to calculate their age based on current MONTH and DOB
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Accepted Solution

by:
Scott Pletcher earned 500 total points
ID: 40387647
DATEDIFF(MONTH, DOB, GETDATE()) / 12
0
 

Author Comment

by:al4629740
ID: 40387650
So I can basically stick whatever date I am comparing to in the GETDATE() section?

For example:

DATEDIFF(MONTH, DOB, GETDATE()) / 12
or
DATEDIFF(MONTH, DOB, '12/1/2014') / 12
or
DATEDIFF(MONTH, DOB, variable) / 12
0
 
LVL 48

Expert Comment

by:PortletPaul
ID: 40387653
So "current month" can be treated as "1st of" the current month, and the calculation method remains the same.

declare @datum as date
set @datum = (select DATEADD(dd, - (DAY(getdate()) - 1), cast(getdate() as date) ) )

select * 
from tblregistrations
WHERE  YEAR(@datum) - YEAR(DOB)
        - ( CASE
               WHEN MONTH(DOB) > MONTH(@datum)
                 OR ( MONTH(DOB) = MONTH(@datum)
                    AND DAY(DOB) > DAY(@datum)
                    )
               THEN 1
               ELSE 0
             END )  < 18

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line 2 above calculates "1st day of current month"
0
 
LVL 69

Expert Comment

by:Scott Pletcher
ID: 40387655
Yep, that should be it, if all you're worried about is the month of the dob.
0
 

Author Comment

by:al4629740
ID: 40387659
Yes, it would be comparing the month of DOB to month of whatever I specify
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