Question

I need to have a sql function which takes a valid SQL Server date an returns the moon-phase for that date. I found a function, but unfortunaley it is in pl-sql which I have no understanding of, I can convert the code as is, but I have no idea how to get the julian date in SQL Server.

This is the skeleton function I want to use

IF OBJECT_ID (N'dbo.fn_phaseOfMoon', N'FN') IS NOT NULL
    DROP FUNCTION dbo.fn_phaseOfMoon;
GO
CREATE FUNCTION dbo.fn_phaseOfMoon (@DATE datetime)
RETURNS VARCHAR(30) AS
BEGIN
    RETURN 'NA';
END
GO

The pl-sql code is located here, can someone please point me in the right direction, or help converting the code?

Answer 1

This is Java code that I’ve changed into MSSQL. See if does the trick for you.

CREATE FUNCTION dbo.fn_phaseOfMoon (@Date datetime)
RETURNS INT
BEGIN

Declare @y int,
        @m int,
        @d int,
        @c int,
        @e int,
        @b int,
        @jd float

Select @y = DatePart(yy, @Date), @m = DatePart(mm, @Date), @d = DatePart(dd, @Date)
    /*
      calculates the moon phase (0-7), accurate to 1 segment.
      0 = > new moon.
      4 => full moon.
      */

    if (@m < 3) 
        Select @y = @y - 1, @m = @m + 12
    Select @m = @m + 1;

    Select @c = 365.25 * @y, @e = 30.6 * @m
    Select @jd = @c+@e+@d-694039.09  /* jd is total days elapsed */
    Select @jd = @jd / 29.53          /* divide by the moon cycle (29.53 days) */
    Select @b = convert(int, @jd)          /* int(jd) -> b, take integer part of jd */
    Select @jd = @jd - @b          /* subtract integer part to leave fractional part of original jd */
    Select @b = (@jd * 8) + 0.5    /* scale fraction from 0-8 and round by adding 0.5 */
    if @b = 8
        Select @b = 0          /* 0 and 8 are the same so turn 8 into 0 */
    return @b
END

I don’t know much about these stuff, so you have to check if the answer’s is correct

Source of Java code : http://www.voidware.com/moon_phase.htm