SDU Tools: Date of Orthodox Easter in SQL Server T-SQL

Some time back, we added DateOfEasterSunday to our free SDU Tools for developers and DBAs. Given it was the Christian Easter Sunday, almost immediately, I got a request for the Greek Orthodox Easter. That date isn’t of course just the Greek one, so we’ve added a new function DateOfOrthodoxEaster.

It’s based on a concept from Antonios Chatzipavlis. Thanks !

It takes a single parameter:

@Year int - the year to find the date for

And the return value is a date.

Find out more

You can see it in action in the main image above, and in the video here. The full current version of the code is also shown below:

You can use our tools as a set or as a great example of how to write functions like these.

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http://sdutools.sqldownunder.com

Latest version of the code

Note: the code might wrap when displayed below.

CREATE OR ALTER FUNCTION SDU_Tools.DateOfOrthodoxEaster
(
    @Year int
)
RETURNS date
AS
BEGIN

-- Function:      Returns the date of Orthodox Easter in a given year
-- Parameters:    @Year int  -> year number
-- Action:        Calculates the date of Orthodox Easter for
-- a given year, adapted from a code example 
-- courtesy of Antonios Chatzipavlis
-- Return:        date
-- Refer to this video: https://youtu.be/QbYx4k0ey8k
--
-- Test examples: 
/*

SELECT SDU_Tools.DateOfOrthodoxEaster(2020);
SELECT SDU_Tools.DateOfOrthodoxEaster(1958);

*/
    RETURN DATEADD(DAY, 13, CAST(CAST(@Year AS varchar(4))
                            + RIGHT('0' + CAST(((((19 * (@Year % 19) + 15) % 30) 
                                                + ((2 * (@Year % 4) + 4 * (@Year % 7) 
                                                - ((19 * (@Year % 19) + 15) % 30) +34) % 7) 
                                                + 114) / 31) AS varchar(2)), 2)
                            + RIGHT('0' + CAST((((((19 * (@Year % 19) + 15) % 30) 
                                                + ((2 * (@Year % 4) + 4 * (@Year % 7) 
                                                - ((19 * (@Year % 19) + 15) % 30) +34) % 7) 
                                                + 114) % 31) + 1) AS varchar(2)), 2) AS date));
END;
GO

2021-02-12