For many system administrators, myself included, Perl is the scripting language of choice. Perl is nearly ubiquitous, available for most operating systems in popular use today. Thanks to the free availability of its source code, hundreds of modules extending its capabilities have been developed. Quite noteworthy among Perl modules is Tim Bunce's DBI (database independent). The Perl DBI provides an API for interfacing with any database, at least any database for which a corresponding DBD (yes, database dependent) module is available.

A quick scan of Perl modules listed on cpan.org, Perl HQ, shows DBD modules for Informix, Oracle, Sybase, IBM's DB2 and many more. Glaringly absent from this list is a DBD module for connecting to a Microsoft SQL server. A DBD::ODBC module has been developed, but using this requires a separate driver manager and suitable drivers. To the best of my knowledge, these are only available for Microsoft's SQL 2000 from third-party vendors, a solution that of course brings the benefits of professional development and support. As it turns out, there is another way.

Thanks to an arrangement with Sybase, Microsoft's SQL server products were developed with the same network communications protocol that Sybase used, namely Tabular Data Stream, or TDS. Through the release of SQL 7.0, Microsoft officially supported Sybase client software with a caveat that such support was at its end. Thus the Perl DBD::Sybase module, compiled with Sybase's freely downloadable client libraries, was able to connect to any Microsoft SQL server until the release of SQL 2000.

With the introduction of TDS 8.0 and legacy support for TDS 7.0 in SQL 2000, compatibility with the Sybase client, using TDS 4.2, is broken. However, the DBD::Sybase module can be built with the TDS libraries from freetds.org, which does support TDS version 7.0, and is used to connect to SQL 2000. Here's how.

I have tested this on Red Hat Linux 7.1 and 7.2. Because this project requires working with source code, you'll need a compiler. GCC, the GNU C compiler, is very conveniently supplied with Red Hat's Linux distribution. Perl and the DBI module are likewise available in RPM form on Red Hat CDs.

First, download DBD-Sybase-0.94.tar.gz to a convenient location on your machine. This is available at cpan.org and also from the author's download page at www.mbay.net/~mpeppler. The FreeTDS source code is available on www.freetds.org. Get freetds-0.53.tgz, the latest revision as of this writing. I strongly recommend reading all the helpful documentation available on these respective sites.

Next, gunzip and untar these downloaded files, then cd to the newly created freetds-0.53 directory and run ./configure --with-tdsver=7.0, which writes a Makefile suitable for compiling FreeTDS on your machine and specifies tds 7.0 as the default protocol.

Now run make:

make
Making all in include
make[1]: Entering directory
         `/home/atrice/freetds-0.53/include'
Making tds_configs.h

and so forth.

Then run make install to install your freshly compiled FreeTDS. By default, it installs to /usr/local/freetds, though you can change this when running configure with the -prefix=(PATH) switch. You must be root to install:

make install
Making install in include
make[1]: Entering directory
         `/home/atrice/freetds-0.53/include'
make[2]: Entering directory
         `/home/atrice/freetds-0.53/include'

and so on. The final comments from make install will be something like:

if [ -f /usr/local/freetds/etc/freetds.conf ]; \
then :; \
else \
/usr/bin/install -c -m 644 freetds.conf
/usr/local/freetds/etc/freetds.conf;
\
fi
make[2]: Leaving directory `/home/atrice/freetds-0.53'
make[1]: Leaving directory `/home/atrice/freetds-0.53'

You have now compiled and installed FreeTDS.

Next, we perform a very similar set of commands to configure and build the DBD:Sybase module. First, however (very important), we must set up an environment variable called SYBASE. This variable will be set to the path of the FreeTDS installation. I am using the bash shell:

export SYBASE=/usr/local/freetds

Confirm the proper setting of the variable:

echo $SYBASE
/usr/local/freetds

Then cd into the DBD-Sybase directory and run Makefile.PL:

perl Makefile.PL
Sybase OpenClient found.
The DBD::Sybase module needs access to a Sybase server
  to run the tests.
To clear an entry please enter 'undef'
Sybase server to use (default: undef):
User ID to log in to Sybase (default: sa):
Password (default: undef):
Note (probably harmless): No library found for -lcs
Note (probably harmless): No library found for -lsybtcl
Note (probably harmless): No library found for -lcomn
Note (probably harmless): No library found for -lintl
Using DBI 1.20 installed in
  /usr/lib/perl5/site_perl/5.6.0/i386-linux/auto/DBI
Writing Makefile for DBD::Sybase

Notice that the Makefile.PL script asks you for information about your Sybase server. It uses this information to write a file called PWD that is used by the test utilities provided with the module. These were designed to run against a Sybase server, not Microsoft, and I did not have much success with the tests. The messages regarding the libraries not found are due to compiling DBD::Sybase with the FreeTDS libraries instead of Sybase's.

Run make, then make install. The last few messages from make install should read as follows:

Installing /usr/share/man/man3/DBD::Sybase.3
Writing /usr/lib/perl5/site_perl/5.6.0/i386-linux/
auto/DBD/Sybase/.packlist
Appending installation info to /usr/lib/perl5/5.6.0/
i386-linux/perllocal.pod

You are done installing DBD::Sybase. Next we'll configure FreeTDS to talk to your SQL 2000 database.

FreeTDS has a configuration file quite logically called freetds.conf. It resides in the freetds installation directory under /etc, so in my case the full path is /usr/local/freetds/etc/freetds.conf. There is a sample Microsoft server configuration already present in this file, and you only need modify it to reflect your server's information. Mine looks like this:

# A typical Microsoft SQL Server 7.0 configuration
[file1]
        host = file1
        port = 1433
        tds version = 7.0

My SQL server is called file1; it runs its database service on the default port of 1433, and I have specified the tds version 7.0. There is a global configuration section in the beginning of this file where you also can set the tds version. Make sure your client machine can resolve the hostname of your database server, or simply use its IP address.

Now we're ready to attempt a connection. Listing 1 is a Perl script written by my colleague Trevor Price that queries the sample database called Northwind. This database is included with a typical SQL 2000 installation. It makes use of a stored procedure called sp_help, which returns information about all the tables in that database. Copy this code into a file called something like testsql.pl, then edit $user and $password to reflect a database account with access to your server.

Listing 1. Trevor Price's Perl Script that Queries the Sample Database Called Northwind

Run the script and you should get an output looking like this:

perl testsql.pl
rows is -1
Alphabetical list of products   dbo     view
Category Sales for 1997 dbo     view
Current Product List    dbo     view
Customer and Suppliers by City  dbo     view
Invoices        dbo     view
Order Details Extended  dbo     view

If you've gotten this far, congratulations! I hope you find this as helpful as we have.