The DATEDIFF Function is used to calculate the difference between two dates. So let’s have a look at a practical example of how to use a DATEDIFF Function in SQL Server
The DATEDIFF Function
The SQL Server DATEDIFF Function is used to calculate the difference between two dates.
Syntax
The syntax of the DATEDIFF built-in date function is as follows :
DATEDIFF(Datepart, Startdate, Enddate)
Here, The “Datepart” parameter is the part of the datetime to calculate the difference of. The Datepart can be any of the following:
Ms Milliseconds
Yy Year
Qq Quarter of the Year
Mm Month
Dy The Day of the Year
Dd Day of the Month
Wk Week
Dw The Day of the Week
Hh Hour
Mi Minute
Ss Second
Example-1
Now you can calculate age with the DATEDIFF function:
Select getdate() as CurrentDate
Go
Declare @CurrentDate datetime = getdate()
Declare @DOB datetime = ‘1986-03-15’
Select DATEDIFF( Year, @DOB, @CurrentDate) as CurrentAgeinYears
Output
Example-2
Now you can see when the second date is later than the first date. The result will be a negative number:
Select datediff(YY, ‘2012-08-05’, ‘2008-06-05’) As Year
Go
Select datediff(Mm, ‘2012-08-05’, ‘2008-06-05’) As Month
Output
