asked
Run query 1st month for previous month else current month
Hi All, What is the best way in sql using datetime format 2012-02-01 00:00:00.000 to select data where on the 1st of the month it returns all data from the previous month i.e. 2012-01-01 00:00:00.000 to 2012-02-01 00:00:00.000, otherwise return data from the 1st of the month to the current date? Thanks for your help! it's a where clause for a report that will be running daily...
First of all you need to realise that date data is not stored in a particular format. It is simply stored as datetime data (actually 8 bytes), and it is only when we read it out of the database does a format get applied. Given that it should be easy to follow that you need a where clause like where ( datepart(dd, getdate()) = 1 --1st of month and yourdatefield >= dateadd(mm, -1, cast(getdate() as date)) --1st of prev month and yourdatefield < cast(getdate() as date) --1st of this month ) or ( datepart(dd, getdate()) 1 -- not 1st of month and yourdatefield >= dateadd(dd, -datepart(dd, getdate())+1, cast(getdate() as date)) --1st of this month and yourdatefield < getdate() --now )
Probably not going to make it :(! You can't use an else statement, but only one of these will be true for a given date. The logic captures both cases (1st or not 1st) and then filters the data dependant on that. Make sense?
I would have approached it a bit different. I would have applied the logic to the dates in variables before moving to the actual statement i.e.
DECLARE @StartDate DATE, @EndDate DATE
IF DATEPART(dd, GETDATE()) = 1 --1st of month
BEGIN
SET @StartDate = DATEADD(mm, -1, GETDATE()) --1st of prev month
SET @EndDate = GETDATE()
END
ELSE
BEGIN
SET @StartDate = DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()) , 0) --1st of this month
SET @EndDate = DATEADD(dd, 1, GETDATE())
END
Then an easy WHERE clause would have been
datefield >= StartDate AND datefield < EndDate
@Kev Riley Absolutely right :) if the current date has to be included then EndDate should be handled the same way.
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