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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-5065) timestampdiff doesn't differentiate between 28 march 2010 and 29 march 2010
Date Wed, 23 Feb 2011 21:28:38 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12998554#comment-12998554
] 

Knut Anders Hatlen commented on DERBY-5065:
-------------------------------------------

What happens here, is that the two date arguments are converted to timestamps with the time
component set to 00:00:00. Because of daylight savings time, the difference between 2010-03-28
00:00:00 and 2010-03-29 00:00:00 is 23 hours, which is less than one day.

Since the arguments to the TIMESTAMPDIFF function are defined as timestamps, I'm not sure
exactly what to expect when the actual arguments are dates.

> timestampdiff doesn't differentiate between 28 march 2010 and 29 march 2010
> ---------------------------------------------------------------------------
>
>                 Key: DERBY-5065
>                 URL: https://issues.apache.org/jira/browse/DERBY-5065
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.7.1.1
>         Environment: windows 7, the bug has been testified using ij tool and usign squirrel
sql. My locales are "France"
>            Reporter: emmanuel chemla
>
> I needed to accomplish a simple task with Derby : computing an interval of days (like
datedif in excel). 
> I used the TIMESTAMPDIFF function, it seemed to work well, until I noticed a strange
behaviour : sometimes the computation is OK, sometimes not. 
> After having searched the trouble, I've found that from TIMESTAMPDIFF's point of view,
the 28 march 2010 is not a different day than the 29 march 2010. 
> You can easily check it with this script in ij tool : 
> -- creating testing environment 
> CONNECT 'jdbc:derby:MyDbTestxyz;create=true';
> CREATE TABLE dummy (beginning DATE, ending DATE); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-04-01', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-31', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-30', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-29', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-28', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-27', '2010-04-01'); 
> INSERT INTO dummy (beginning, ending) VALUES ('2010-03-26', '2010-04-01'); 
> -- 
> -- checking the odd behaviour 
> SELECT beginning, ending, {fn timestampdiff(SQL_TSI_DAY, beginning, ending )} AS "interval
in days" FROM dummy; 
> -- 
> --  cleaning 
> DROP TABLE dummy 
> You'll get this result : 
> beginning	ending	interval in days 
> 2010-04-01;	2010-04-01;	0 
> 2010-03-31	;	2010-04-01;	1 
> 2010-03-30	;	2010-04-01;	2 
> 2010-03-29	;	2010-04-01;	3   
> 2010-03-28	;	2010-04-01;	3  ??????
> 2010-03-27	;	2010-04-01;	4  !
> 2010-03-26	;	2010-04-01;	5  !

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