Comparison between DateTime Value

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Comparison between DateTime Value

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Posted - 2002-03-22 : 09:12:32

DrMaltz writes "Recently, I've been struggling with trying to compare 2 datetime values. The problem: There are times when one of the datetime variables is null so that causes the comparison to fail.. I even tried to add the IsNull function to my select statement to replace the value with a default if the datetime returned null, but this has not worked. Am I doing something incorrectly..

In the sample code, the comparison will fail because TestTbl has does not return any records. It still fails even if I add the IsNULL to the select statement. Here's a sample of my code..

CREATE TABLE TestTbl(
ActualTime datetime NULL
)
go

CREATE TABLE TestTbl2(
ActualTime datetime NULL
)
go

INSERT TestTbl2 VALUES ('03/19/2002 9:40:00')

Declare @t1 datetime
Declare @t2 datetime

Select @t1 = Max(isNull(ActualTime,'03/19/2002 00:00:00')) from TestTbl

Select @t2 = Max(ActualTime) from TestTbl2

if @t1 > @t2
Print "t1 is greater"
else
if @t2 > @t1
Print "t2 is greater"

any thoughts would be appreciated.. Thanks in advance."

Jay99

468 Posts

Posted - 2002-03-22 : 09:42:37


INSERT Testtbl VALUES (NULL)

There is a difference between haveing nothing in the table and have a row with a value of NULL . . . . that is to say, if you table has a rowcount of 0, selecting max(whatever) will always return nothing . . .

Jay
<O>

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