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timestamp function in db2

Posted on 2009-07-13
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Last Modified: 2012-08-14
I found strange things when using timestamp funtion in writing a query for db2 sql that had the following clause in the sql statement
AND   timestamp('2009-06-01','00:00:00') <=  startdatetime AND   StartDateTime < timestamp(date('2009-06-30') + 1 day,'00:00:00')

same above statement when it was written as follows
AND startdatetime >= '2009-06-01-00.00.00' and startdatetime <= '2009-06-30-00.00.00' - produced different results  - first one produced more aggregate records for evaluation then the second - what differences that db2 does in using a timestamp fuction as against direct comparisons of datetime field? (startdatetime is defined as timestamp of length 10)
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Question by:mahjag
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4 Comments
 
LVL 18

Expert Comment

by:daveslash
ID: 24843866

On one clause you have "less-than", but on the other clause you have "less-than-or-equal-to"

HTH,
DaveSlash


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LVL 45

Expert Comment

by:Kent Olsen
ID: 24843951
Hi mahjag,

What Dave said.

Also, the format of the datetime is incorrect.  The value '2009-06-01-00.00.00'  should be '2009-06-01.00.00.00'.  Note that a period should separate the date and time values, not a hyphen.  An improperly formatted datetime will affect the comparison in an ugly way.


Good Luck,
Kent
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LVL 18

Accepted Solution

by:
daveslash earned 125 total points
ID: 24844353

That's realy interesting.  ( see below )

On DB2 for i, this works:
 
select *
from   deleteme
where  aTS >= '2009-07-01-00.00.00'
  and  aTS <= '2009-07-31-00.00.00'
;
 
But, this doesn't:
 
select *
from   deleteme
where  aTS >= '2009-07-01.00.00.00'
  and  aTS <= '2009-07-31.00.00.00'
;
 
[SQL0180] Syntax of date, time, or timestamp value not valid.

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LVL 45

Expert Comment

by:Kent Olsen
ID: 24845151
Hi Dave,

Wow.  I've had scads of queries fail due to badly formatted date, time and/or datetime values.  I've never seen the behavior where a timestamp was accepted in that format.

Of course, I'm an LUW kind of guy.   :)    (Where a full timestamp really needs microseconds ('.000000') appended after the time.)


Kent
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