A fair year-to-date comparison needs the same dates from last year. Here is a short query, plus the leap day trap.
SQL SERVER – 2008 – Get Current System Date Time
Several ways to get the current system date time in SQL Server 2008, from GETDATE to the newer functions, with a quick video on the topic.
SQL SERVER – 2008 – Find Current System Date Time and Time Offset
SQL Server 2008 adds SYSDATETIMEOFFSET, which returns the current system date time along with its time offset from GMT. One line shows how.
How to Calculate Age Correctly in SQL Server
Calculate Age in SQL Server by counting completed birthdays, not calendar years. This post compares DATEDIFF, a DATEADD correction and a compact integer version on a bike club table, handles February 29 birthdays and ends with a reusable function for age on any date.
SQL SERVER – 2008 – SQL Server Start Time
SQL Server 2008 records when it started in sys.dm_os_sys_info. One SELECT of sqlserver_start_time gives you the SQL Server start time. It does not work on 2005.
DATETRUNC: Use ISO Week Boundaries With Explicit Date Types
DATETRUNC can give an ISO week its Monday boundary without changing session settings. I also keep the input date type explicit. A boundary calculation should reveal both its calendar rule and its return type.
SQL SERVER – SQL SERVER – UDF – Get the Day of the Week Function Part 4
In Day of the Week Function Part 4, I answer why I write a UDF when DATENAME exists (I just like it) and show the one line DATENAME version.