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Find records with a specific date

Posted on 2008-10-29
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Last Modified: 2012-05-05
Hi,

I'm trying to come up with the best way of finding records that have a datetime field = 1 date.

i.e.
declare @startdate as datetime
set @startdate = '28/10/2008'
select * from myTable Where fldMsgDate = @startdate

This doesnt work because the msgdate has minutes & seconds in it.

declare @startdate as datetime
set @startdate = '28/10/2008'
select * from myTable Where cast(fldMsgDate as int) = cast(@startdate as int)

does, as does the convert

select * from myTable Where convert(varchar(10),fldMsgDate,101) = convert(varchar(10),@startdate,101)

(Howeever they come up with different totals!).

Is there a function that I'm missing or do you really have to use cast or convert?

Whats teh best way? I've been struggling with this for years!  Thanks.


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Question by:jmsjms
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 22833439
small change:
declare @startdate as datetime
set @startdate = '28/10/2008'
select * from myTable Where fldMsgDate >= @startdate
 and fldMsgDate < dateadd(day, 1, @startdate)

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Expert Comment

by:jfmador
ID: 22836090
Hello I'm not sure about the @startdate you set it using dd/mm/yyyy format, I don't know how the Sql Server will convert it. What happen if you use '05/11/2008', would it be the nov 5th or may 11th?

Maybe angelll could give us an advice about this.

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Author Comment

by:jmsjms
ID: 22836687
So. from a performance view, Is it better to have two conditions in the where rather than use a convert to remove the minutes/seconds from the datetime field?

Could I be cheeky and also ask how would you handle  the WHERE statement if the @startdate = getdate() ?

Many thanks
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LVL 143

Accepted Solution

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Guy Hengel [angelIII / a3] earned 1000 total points
ID: 22836776
>So. from a performance view, Is it better to have two conditions in the where rather than use a convert to remove the minutes/seconds from the datetime field?

better to have the 2 conditions. removing the time from the field in the where condition will just make your query a full-table scan.

>Could I be cheeky and also ask how would you handle  the WHERE statement if the @startdate = getdate() ?

same method... or inline:

select * from myTable Where fldMsgDate >= convert(datetime, convert(varchar(10), getdate(), 120), 120)
 and fldMsgDate < dateadd(day, 1, convert(datetime, convert(varchar(10), getdate(), 120), 120))

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Author Comment

by:jmsjms
ID: 22839264
Thanks, thats very useful with the amount of records I have to handle.

So using >= and < is better than between ... and ... for dates?
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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 22839354
>So using >= and < is better than between ... and ... for dates?
no, that part is the same...
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Author Closing Comment

by:jmsjms
ID: 31511288
Thanks very much!
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