Sender: tgl@mythos.jpl.nasa.gov
Message-ID: <36E53C2E.C2E59616@alumni.caltech.edu>
Date: Tue, 09 Mar 1999 15:20:14 +0000
From: "Thomas G. Lockhart" <lockhart@alumni.caltech.edu>
Organization: Caltech/JPL
MIME-Version: 1.0
To: hoelc@pd.jaring.my
CC: pgsql-general@hub.org
Subject: Re: [INTERFACES] the last row in a table
References: <36E163D7.CD95C55A@pd.jaring.my>
	<87emn1fwsq.fsf@tolikus.hq.aaanet.ru>
	<36E50F4A.CB527B78@pd.jaring.my>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

> I am developing a database with PostgreSQL in Linux, and using ecpg to 
> write the C program to communicate with the database.
> One of my application need to get the data from the last row in a 
> table. Is there any function or command that can tract which is the 
> last row of data in a table?

SQL is a set-oriented language. One should probably not assign any
significance to a storage order of rows.

It *is* possible to order the results of a query, and then your
first/last qualities do have meaning. I would suggest ordering your
query (perhaps on a "row update time" if by "the last row" you mean "the
more recently entered row") using the "DESC" qualifier in the ORDER BY
clause, then use a cursor to pick up the first row returned.

Good luck.

                     - Tom