How do I convert birthdate to age in a sql statement

Datediff(yyyy,getdate(),birthdate)

That will give num years diff aka Age.

Above comment was assuming Birthdate as Datetime column.
If not convert it into Datetime and then do Datediff..

And note that this would tell the completed years and not the running years..
If you need it to be compared for running years, then Add 1 to make it work like

and DATEDIFF(YY, Birthdate, getdate()) + 1 between @AgeMin and @AgeMax

CGLuttrell,
    Datediff(yyyy,getdate(),birthdate) would give age in negative values..
Startdate should be placed first and then enddate..

Hope you agree with this

@rrjegan17,  I agree, was working quickly from mobile and got it backwards.

Here are 2 formulas I use to get the exact "age":

Not taking leap years into consideration (fine for most scenarios):
select cast(datediff(d, Birthdate, getdate()) AS DECIMAL (8,1))/365

Taking leap years into consideration (more precise):
select cast(datediff(d, Birthdate, getdate()) AS DECIMAL (8,1))/365.25

bolenka,
   No responses from your end..

sorry...posted late last night...had to go to bed...I apologize...let me take a look at all responses this morning...and get back to you.

Ok.. No Probs..
Waiting for your responses..

aikimark: I am reading your post, and am trying that one out, and so far it seems to work...but, so I am learning...what is the difference between what you posted and say, what victoria posted???

btw, I appreciate you putting all the code I would need for the where clause....there was a missing parentheses, but I figure it out no biggie.

thanks, to everyone...so so much...i am not quite done yet, but will let you know about points asap.

bolenka,
   Have you read my comment at the beginning..

I think it depends on what you are comparing to for your parameters.  If your AgeMin and AgeMax are numbers (like you want everyone between 40 and 60 years old), you could use my code like so:

SELECT FirstName, LastName, City, [State], ZipCode, Comment, Birthdate 
FROM ProfilePreferences 
WHERE ZipCode 
IN( some other code here) 
and Gender=@Gender
and cast(datediff(d, Birthdate, getdate()) AS DECIMAL (8,1))/365 between @AgeMin and Age<=@AgeMax

                                              

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yes, thank you rrjegan17, by running years, you mean like the date you are and then adding all extra days ...like, I turn 36 tomorrow, but I am not yet 36 today, but on my birthday tomorrow, I will be 36...right?

so that would be in the where clause as well??? I will try that also right now. Thanks so much.

right victoria: my age min and max are numbers...that is correct....because they are just being passed in from an aspx form...like

I want this data where the people I am looking for are between ages 18 (dropdownlist) and 32(dropdown list), but in the database, when they create their profile, I don't want them to have to enter in their age. The database stores the birthdate in a datetime field. So, that is why I want it to convert to age and compare the age to the birthdate...so I guess the birthdate would have to be converted to age for comparison, right?

Yes.. you are correct..

Comment 25297041 is with completed years and 25297047 is with running year.
Just replace those lines in your actual query to make it work.

ok, i am still looking..then will award pts. thanks so much to everyone.

@Bolenka

You either convert the birthdate into an age (at a specific date) or you convert the (integer) min and max age to dates.  If this is a big table, a stored proc can initialize two date variables from the two age parameters, comparing each row's birthdate value without any more data conversions.  This should perform much faster than converting every row's birthdate value into an age.

aikimark: aha, gotcha. see...that is the stuff I dont know about...I really need to learn which sql queries have more/less impact on performace. Any general rules about this? Or is it too broad of a subject? thanks again.

I think too broad for this current discussion.  After we've solved your problem, open a new question to get direction and resources for performance-related questions.

ok thanks.