Wednesday, October 10, 2007

SQL Teaser: Guess the output

What do you think will be the output?


DECLARE @d datetime
SET @d = '20071010'

SELECT DATEADD(yy, DATEDIFF(yy, 0, @d)+1, -1)

After that run this to see how to get first and last days for years, quarters, months and weeks(be careful of ISO weeks!)

DECLARE @d datetime
SET @d = '20071010'

SELECT DATEADD(yy, DATEDIFF(yy, 0, @d), 0) as FirstDayOfYear,
DATEADD(yy, DATEDIFF(yy, 0, @d)+1, -1) as LastDayOfYear,
DATEADD(qq, DATEDIFF(qq, 0, @d), 0) as FirstDayOfQuarter,
DATEADD(qq, DATEDIFF(qq, 0, @d)+1, -1) as LastDayOfQuarter,
DATEADD(mm, DATEDIFF(mm, 0, @d), 0) as FirstDayOfMonth,
DATEADD(mm, DATEDIFF(mm, 0, @d)+1, -1) as LastDayOfMonth,
DATEADD(wk, DATEDIFF(wk, 0, @d), 0) as FirstDayOfWeek,
DATEADD(wk, DATEDIFF(wk, 0, @d)+1, -1) as LastDayOfWeek

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