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	<META NAME="AUTHOR" CONTENT="Charles Morrison">
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<H3 ALIGN=CENTER>A neophyte's guide to getting unixODBC and
Mysql/MyODBC working 
</H3>
<H4>Introduction</H4>
UnixODBC is an idea whose time has
come. It holds many promises for those of us who use databases in our
daily work and would like to do more of that work on Linux or one of
the UNIX variants. Those coming from a windows background will
rapidly discover that it can be much more involved setting up a
working Unix based database than they are used to. They will also
discover a world of great advantages too; stability, scalability and
freely available source code are values not easily dismissed.
This document is designed to help
people set up and use unixODBC. My database of choice is MySQL, which
I have used with great success for several years, and it is the
database I will discuss setting up
ODBC is an interface by which programs
and programmers can communicate with any database which has an ODBC
driver. While most databases have one or more APIs in various
programming languages, ODBC allows the same programming code to talk
with numerous types of databases. (ODBC is not the only interface to
do this, but it is very widely used and supported)
<H4>Getting Started</H4>
UnixODBC is available in source code
only. This means that you download a tar file from
<A HREF="http://www.unixODBC.org/">http://www.unixODBC.org</A> ,
extract it, compile it, and install it. Before you do so though you
need some other things.
<H4>Prerequisets: 
</H4>
<OL>
	<LI>The Qt toolkit version 2.x sources from <A HREF="http://www.troll.no/">http://www.troll.no</A>
	. Make sure it is version 2 or higher !
	<OL>
		<LI>Download the Qt v2 sources.
		<LI>Extract the sources to somewhere, usually this is done by
		placing the tar file in a directory like /usr/local or /opt and
		using the command. tar zxvf qt-2.0.1.tar.gz to
		extract the files. This will create a subdirectory qt-2.0.1 .
		Remember that only root can normally write to /usr/local or /opt.
		This is an exaple, use the name of the file you have.
		<LI>Compile the sources. Assuming you have a relatively recent
		version of Linux with all the appropriate stuff (libg++, gcc or
		egcs etc) You issue 3 commands from the qt-2.0.1
		directory. ./configure make make install
		<LI>This last command is scary since it will install the new
		libqt into places where any old v1.4x libqt may exist. Rest assured
		that the full name of the library is different and it will not
		overwrite your existing libqt. It should choke on rewriting the
		symlink to libqt.so and thus not mess up your existing Qt / KDE
		apps. If it does rewrite this link, you will need to set it back to
		its original link.
		<LI>For more information, see <A HREF="http://www.troll.no/">http://www.troll.no</A>
		. Please don't bother the unixODBC people for instructions on
		setting up Qt.
	</OL>
</OL>
<OL START=2>
	<LI>A Database - in this case MySQL from <A HREF="http://www.mysql.com/">http://www.mysql.com</A>
	<OL>
		<LI>Again, I strongly suggest you get the sources and compile
		them yourself. The process is similar if not identical to that for
		Qt described above. By default MySQL installs it's executable files
		in /usr/local/bin, it's include files (source
		headers) in /usr/local/include/mysql and it's
		libraries in /usr/local/lib/mysql. The actual
		database files are in /usr/local/var.
		<LI>Before you can use MySQL, you need to run
		 /usr/local/bin/mysql_install_db as root to set up
		the system tables. To actually start the database, run
		 /usr/local/bin/safe_mysqld &amp;
		<LI>MySQL comes with very extensive documentation. Refer to it
		for questions on compiling, installing and using MySQL. This is
		expecially true for permissions. If the permissions aren't correct,
		no interface will work.
	</OL>
</OL>
<H4>Installing unixODBC</H4>
<OL>
	<LI>As mentioned before, get the source tar file from
	<A HREF="http://www.unixodbc.org/">http://www.unixodbc.org</A> . As
	root, move the tar file to /op or /usr/local or where ever you want
	the source to reside. Untar the file and run the following commands
	from the command line in the unixODBC source
	directories: ./configure ./make ./make
	install
	<LI>Assuming that you have all the libraries and tools that it
	needs, you should be breezing through this compile. Certainly after
	all that practice with Qt and MySQL this should be old hat. UnixODBC
	takes quite a while to compile, actually all of these packages do.
	Relax and enjoy it. 
	
</OL>
<H4>Installing a Driver</H4>
UnixODBC by itself isn't a whole lot
of good without a driver. MySQL has an ODBC driver named MyODBC but
it isn't included with the current edition of unixODBC, so you have
to get it and compile it yourself. I'll be referring to version
2.50.24, the latest as of this writing. The installation is much the
same as the other packages, but you need to give configure some
options. It will prompt you for the path to the MySQL sources if you
don't specify the path, but you also have to supply the
--with-unixODBC=&lt;your unixODBC directory here&gt; flag. The
following is from the MyODBC INSTALL file: 

 To make configure look for
unixODBC instead of iODBC, use
 --with-unixODBC=DIR
 Where DIR is where unixODBC
is installed.
 And (as usual), if the
unixODBC headers and libraries aren't located
 in DIR/include and DIR/lib,
use
 
--with-unixODBC-libs=LIBDIR --with-unixODBC-includes=INCDIR
 You might want to specify a
prefix other than /usr/local for installation, I, for example
keep my ODBC drivers in /usr/local/odbc/lib, so I add
 --prefix=/usr/local/odbc
So here is my configure line:
./configure
--with-unixodbc=/usr/local --with-mysql-sources=/usr/local/mysql
Running make and then make
install puts the resulting library: libmyodbc-2.50.23.so
into /usr/local/lib. WAIT A MINUTE ! Didn't I say it was version
2.50.24 ? Yes, I did. However, unless you want to go in and change
the version info in the source code, it will create the library with
that name. I don't consider this a big deal and so I didn't mess with
it.
If you omit the --with-mysql-sources
flag, configure will fail. If you omit the --with-unixodbc
flag, configure will complete and MyODBC will compile. However, it
will not work correctly when using it with unixODBC. The problems
described below occurred when I omitted this flag: 1) If the
DSN (Data Source Name) you create is also the name of a database, the
driver points to that database no matter what you specify the
database to be. 2) If the DSN is not the name of an existing
database, it will fail, not allowing you to login to the database.
The trace log file will tell you that it couldn't find a database
with the name of the DSN. This is confusing if you specified a valid
database name in the .odbc.ini file . 

When using the --with-unixodbc
flag, These problems dissappear and it works the way it should. 

A note: MyODBC does not support ODBC
version 3 as of version 2.50.24 . When writing programs that utilize
this driver, I have had success with specifying V_OD_ODBC2 when
calling SQLSetEnvAttr(...) .
<H4>Setting up unixODBC</H4>
At long last we come to actually
setting up unixODBC and using it. While most of this information
exists on the unixODBC web pages and user's guide, I found it
difficult to find and follow, so I repeat it here in hopes that it
will be made clearer.
UnixODBC consists of a lot of
libraries, installed in /usr/local/lib, and a few executable
files (binaries) installed into /usr/local/bin. These
executable files are ODBCConfig, DataManager, and
odbcinst. 

In order to get unixODBC running, do these things in this
order:
Do this as root...
In an xterm, type ODBCConfig . This is
a GUI program and must be run in an X session. At the very least you
need to set up a driver to use. The drivers will be specific to one
database application, like MyODBC is specific to MySQL. In addition
to this, you need to specify a setup file to use for this drive. The
setup files are the /usr/local/lib/libodbc*S.so libraries
where * signifies the database application, so
/usr/local/lib/libodbcmyS.so is the &quot;setup file&quot; for
MyODBC. The driver (not the setup file) is
/usr/local/lib/libmyodbc-2.50.23.so. 

To set up the
driver, run ODBCConfig as root, go to the drivers tab and click on
&quot;New&quot;. The following are the settings I use...
Name: myodbc Description: MySQL
driver. Driver: /usr/local/lib/libmyodbc-2.50.23.so Setup:
/usr/local/lib/libodbcmyS.so FileUsage: 1
You should have a
driver set up before setting up a DSN. After having done so, you may
want to set up a system DSN. You do this by selecting the &quot;System
DSN&quot; tab, clicking on 'New', specifying the driver to use and
filling in the required information. You will want to select the
driver name you just defined as the Driver in the first screen that
displays, and click OK.
Doing this as
root will create and edit the /usr/local/etc/odbcinst.ini (for
the driver info) and /usr/local/etc/odbc.ini (for the system
DSN) files. Early versions of unixODBC would put these files in /etc,
and you can still use a configure option : --sysconfdir=/etc
to put those files in that location.
Do this as a normal user: 

The process for setting up a user DSN
is identical to setting up a system DSN. You simply select the &quot;User
DSN&quot; tab in ODBCConfig and fill out the required fields. The
following is how I filled out a User DSN.
Name: mysqltest Description:
myodbc Driver: myodbc Trace: Yes TraceFile: mysql.log Host:
localhost Port: 3306 Socket: Database: test
This will create and edit a file named
~/.odbc.ini . Since the test database comes without any tables, you
may want to specify mysql as the database instead, so you can see the
tables when running DataManager.
Run DataManager
Now you should be able to run
DataManager and see your drivers, DSNs and tables for each DSN. See
the unixODBC web site for screen shots of what it should look like. 

OK, Now What ?
UnixODBC is not so much an end user
program, but rather an intermediary between a program and one or more
databases. There is information in the unixODBC documentation for
example, about setting up StarOffice to use an ODBC connection. I am
in the process of writing a <A HREF="http://www.info2000.net/~cmorrison/databuilder.html">program</A>
that makes use of unixODBC and numerous others are as well. It may
well be that in time unixODBC will be included in numerous Linux
distributions and installed by default. Until that time I hope that
this document helps you get this sofware up and running.
Charles
Morrison cmorrison@info2000.net
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