SDU Tools: Date of Easter Sunday
One of the endless challenges when working with databases (and not just SQL Server databases) is processing dates and times.
While there are some good date-handling functions in the T-SQL language, there are many more gaps in what’s offered. This month, we’ve filled another one of those gaps.
In Australia, whether staff are religious or not, the Christian Easter is associated with a four-day weekend for most workers except those in retail ie: Friday (Good Friday), Saturday (Holy Saturday), Sunday (Easter Sunday), and Monday (Easter Monday). For many, it looks like this:
[caption id=“attachment_2701” align=“alignnone” width=“520”]
Image by Leio McLaren[/caption]
If you are creating a date dimension in a data warehouse, you might need to know when holidays like this occur. I mentioned in an earlier post that not everyone can tell you the current rules for Leap Years (so we built a tool for that), but even those that can would typically struggle if you asked them how to work out when Easter occurs in each year.
Claus Tøndering has an amazing set of pages called his Calendar FAQ. I highly encourage you to read it. The background provided for how various calendars and dates work is quite amazing. For what we need for this tool though, Claus describes how to calculate the date for Easter Sunday here:
http://www.tondering.dk/claus/cal/easter.php#wheneasterlong
As part of our free SDU Tools for developers and DBAs, we’ve added an implementation of the calculations that he describes on that page, in a function called DateOfEasterSunday. (If you need to do this in other languages, Claus also has an algorithm section that might help but we just decided to implement the T-SQL from his logic instead).
You can the tool used in the main image above, and can watch it in action here:
For more details on our free SDU Tools, or to register for them, please follow this link:
http://sdutools.sqldownunder.com
2018-02-07