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From "Jack Klebanoff (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-81) Datetime datatypes should allow arithmetic operations on them.
Date Tue, 24 May 2005 21:37:55 GMT
     [ http://issues.apache.org/jira/browse/DERBY-81?page=comments#action_66203 ]
     
Jack Klebanoff commented on DERBY-81:
-------------------------------------

As of revision 178061 Derby supports the ODBC/JCBC TIMESTAMPADD and TIMESTAMPDIFF escape functions.
So the query in the request can be written as

  SELECT * FROM log
  WHERE modified_time > TIMESTAMPADD( SQL_TSI_MONTH, 1, CURRENT_TIMESTAMP)

Unfortunately, the major SQL databases all seem to implement datetime arithmetic in different
and incompatible ways. The ODBC/JDBC escape functions, though somewhat awkward, are the closest
thing to a common denominator here.

> Datetime datatypes should allow arithmetic operations on them.
> --------------------------------------------------------------
>
>          Key: DERBY-81
>          URL: http://issues.apache.org/jira/browse/DERBY-81
>      Project: Derby
>         Type: New Feature
>   Components: SQL
>     Versions: 10.0.2.0
>  Environment: Generic
>     Reporter: Satheesh Bandaram
>     Assignee: Jack Klebanoff

>
> Datetime datatypes in Derby are date, time and timestamp. Currently Derby doesn't allow
any arithmetic operations on them, limiting their use. It would be great to allow statements
like:
>    SELECT * FROM log 
>    WHERE modified_time > CURRENT_TIMESTAMP - 1 MONTH
> Commercial databases like Oracle, DB2 and mySQL also have this feature. SQL standard
allows these operations along with INTERVAL types. Since Derby doesn't have INTERVAL datatypes,
I would like to propose datetime arithmetic to Derby without INTERVALs.
> It should be possible to add, subtract datetime datatypes with a constant like '1 MONTH'
(called a duration or INTERVAL in SQL standard). It should also be possible to subtract datetime
types where the semantics are allowed according to SQL standard specification.

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