CELKO (9/27/2010)

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Alexander Kuznetsov (9/24/2010)

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CELKO (9/23/2010)

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I still prefer Julianizing the business days to make the math easier

CREATE TABLE Calendar

(cal_date DATE NOT NUL PRIMARY KEY,

julian_business_nbr INTEGER NOT NULL,

...);

INSERT INTO Calendar

VALUES ('2007-04-05', 42),

('2007-04-06', 43), -- good friday

('2007-04-07', 43),

('2007-04-08', 43), -- Easter sunday

('2007-04-09', 44),

('2007-04-10', 45); --Tuesday

To compute the business days from Thursday of this week to next

Tuesday:

SELECT (C2. julian_business_nbr - C1. julian_business_nbr)

FROM Calendar AS C1, Calendar AS C2

WHERE C1.cal_date = '2007-04-05',

AND C2cal_date = '2007-04-10';

Yes, we do it too. When a new holiday comes up, like President Ford's funeral, we update all those future numbers.

The updating is not much of a problem:

1) New holidays do not occur very often, per one or two per decade at most. But queries about business days occur very frequently.