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From: Vivek Khera <[email protected]>
Newsgroups: comp.lang.perl.announce,comp.lang.perl.misc
Subject: new Postgres95 module
Followup-To: comp.lang.perl.misc
Date: 21 Oct 1996 15:23:12 GMT
Organization: Khera Communications, Inc., Rockville, MD
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Xref: news.cs.hut.fi comp.lang.perl.announce:460 comp.lang.perl.misc:50618

I got tired of writing C-like code in my Perl programs using the Pg package,
so I wrote a new and improved interface that is more Perl-like.  It is loosely
based on the way the MsqlPerl module works, so it should make for easy porting
of those programs (which is also one of the reasons I wrote this...)

Below is the documentation for the module as generated by pod2text.

To fetch your very own copy, get the file

 ftp://ftp.kciLink.com/pub/PostgresPerl-1.1.tar.gz

unpack it, then run "perl Makefile.PL; make".

To test it, set the environment variable PGHOST to the host of the server
running postgres (if other than the machine which you are on) and then "make
test".  Then all that's necessary is a make install and you've got yourself a
nice perl interface to Postgres95!  It does, however, require Perl 5.003
(though 5.002 *might* work -- I don't know).

Please let me know of any problems with the code or any improvements you may
have or like to have.

Once the portability issues are ironed out (if there are any) I'd like to
donate this to the Postgres95 project for inclusion in the next release.


                                                               v.

--------------------


NAME
   Postgres - Perl interface to the Postgres95 SQL database engine

SYNOPSIS
    use Postgres;

    $conn = db_connect($database,$host,$port)
      or die "could not connect -- $Postgres::error";

    print "Connected Database: ", $conn->db();
    print "Connected Host: ", $conn->host();
    print "Connection Options: ", $conn->options();
    print "Connected Port: ", $conn->port();
    print "Connected tty: ", $conn->tty();
    print "Connection Error Message: ", $conn->errorMessage();


   This method is identical to PQreset(conn)

    $conn->reset();


   This method executes an SQL statement or query.

    $query = $conn->execute($sql_statement)
      or die "Error -- $Postgres::error";


   Retrieve the values from a SELECT query.

    @array = $query->fetchrow();


   Get information from the results of the last query.

    $val = $query->cmdStatus();
    $val = $query->oidStatus();


   Calling the following functions on a result handle that is not from a
   SELECT is undefined.

    $val = $query->ntuples();
    $val = $query->nfields();
    $val = $query->fname($column_index);
    $val = $query->fnumber($column_name);
    $val = $query->ftype($column_index);
    $val = $query->fsize($column_index);


   These functions are provided for completeness but are not intented to be
   used. The fetchrow() method will return `undef' for a field which is
   null.

    $val = $query->getvalue($tuple_index,$column_index);
    $val = $query->getlength($tuple_index,$column_index);
    $val = $query->getisnull($tuple_index,$column_index);


DESCRIPTION
   This package is designed as close as possible to its C API counterpart.
   The C Programmer Guide that comes with Postgres describes most things
   you need.

   The following functions are currently not implemented: PQputline(),
   PQgetline(), PQendcopy(), PQtrace(), PQendtrace(), and the asynchronous
   notification. I do not believe that binary cursors will work, either.

   Once you db_connect() to a database, you can then issue commands to the
   execute() method. If either of them returns an error from the underlying
   API, the value returned will be `undef' and the variable
   `$Postgres::error' will contain the error message from the database. The
   `$port' parameter to db_connect() is optional and will use the default
   port if not specified. All environment variables used by the PQsetdb()
   function are honored.

   The method fetchrow() returns an array of the values from the next row
   fetched from the server. It returns an empty list when there is no more
   data available. Fields which have a NULL value return `undef' as their
   value in the array. Calling fetchrow() or the other tuple-related
   functions on a statement handle which is not from a SELECT statement has
   undefined behavior, and may well crash your program. Other functions
   work identically to their similarly-named C API functions.

 No finish or clear statements

   Whenever the scalar that holds the statement or connection handle loses
   its value, the underlying data structures will be freed and appropriate
   connections closed. This can be accomplished by performing one of these
   actions:

   undef the handle
   use the handle for another purpose
   let the handle run out of scope
   exit the program.

 Error messages

   A global variable `$Postgres::error' always holds the last error
   message. It is never reset except on the next error. The only time it
   holds a valid message is after execute() or db_connect() returns
   `undef'.

PREREQUISITES
   You need to have the Postgres95 database server installed and configured
   on your system to use this module.

   Be sure to set the proper directory locations in the `Makefile.PL' file
   for your installation.

AUTHOR
   Vivek Khera (`[email protected]'). Many ideas were taken from the MsqlPerl
   module.


--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Vivek Khera, Ph.D.                        Khera Communications, Inc.
Internet: [email protected]               Rockville, MD       +1-301-258-8292
PGP/MIME spoken here                      http://www.kciLink.com/home/khera/

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