Re: cross-database time extract?

On Monday 28 December 2009 12:13:46 pm Greenhorn wrote:
> 2009/12/29 Israel Brewster <israel(at)frontierflying(dot)com>:
> > On Dec 24, 2009, at 12:53 PM, Adrian Klaver wrote:
> >> On Thursday 24 December 2009 1:44:58 pm Israel Brewster wrote:
> >>> This is sort of a PostgreSQL question/sort of a general SQL question,
> >>> so I apologize if this isn't the best place to ask. At any rate, I
> >>> know in PostgreSQL you can issue a command like 'SELECT
> >>> "time"(timestamp_column) from table_name' to get the time part of a
> >>> timestamp. The problem is that this command for some reason requires
> >>> quotes around the "time" function name, which breaks the command when
> >>> used in SQLite (I don't know about MySQL yet, but I suspect the same
> >>> would be true there). The program I am working on is designed to work
> >>> with all three types of databases (SQLite, PostgreSQL, and MySQL) so
> >>> it would be nice (save me some programing) if there was a single SQL
> >>> statement to get the time portion of a timestamp that would work with
> >>> all three. Is there such a beast? On a related note, why do we need
> >>> the quotes around "time" for the function to work in PostgreSQL? the
> >>> date function doesn't need them, so I know it's not just a general
> >>> PostgreSQL formating difference. Thanks :)
> >>> -----------------------------------------------
> >>> Israel Brewster
> >>> Computer Support Technician II
> >>> Frontier Flying Service Inc.
> >>> 5245 Airport Industrial Rd
> >>> Fairbanks, AK 99709
> >>> (907) 450-7250 x293
> >>> -----------------------------------------------
> >>
> >> select cast(timestamp_column as time) from table_name
>
> you could try select timestamp_column::time from table_name

That would work in Postgres, but the OP was looking for a cast method that would
also work in MySQL and SQLite. The cast(value as type) is SQL standard :) The
question remains why SQLite is not behaving correctly? Datetime awareness in
SQLite is still relatively new, I will have to do some exploring on that issue.

--
Adrian Klaver
aklaver(at)comcast(dot)net