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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>SQL Module - Drivers</h1>
<p> <!-- toc -->
<ul>
<li><a href="#1"> Introduction
</a>
<li><a href="#2"> Building the drivers using configure
</a>
<li><a href="#3"> Building the plugins manually
</a>
<ul>
<li><a href="#3-1"> QMYSQL3 - MySQL 3.x
</a>
<ul>
<li><a href="#3-1-1"> General informations
</a>
<li><a href="#3-1-2"> How to build the plugin on Unix/Linux
</a>
<li><a href="#3-1-3"> How to build the plugin on Windows
</a>
</ul>
<li><a href="#3-2"> QOCI8 - Oracle Call Interface
</a>
<ul>
<li><a href="#3-2-1"> How to build the plugin on Unix/Linux
</a>
<li><a href="#3-2-2"> How to build the plugin on Windows
</a>
</ul>
<li><a href="#3-3"> QODBC3 - Open Database Connectivity
</a>
<ul>
<li><a href="#3-3-1"> General informations
</a>
<li><a href="#3-3-2"> How to build the plugin on Unix/Linux
</a>
<li><a href="#3-3-3"> How to build the plugin on Windows
</a>
</ul>
<li><a href="#3-4"> QPSQL7 - PostgreSQL version 6 and 7
</a>
<ul>
<li><a href="#3-4-1"> General information
</a>
<li><a href="#3-4-2"> How to build the plugin on Unix/Linux
</a>
</ul>
<li><a href="#3-5"> QTDS7 - Sybase Adaptive Server and Microsoft SQL Server
</a>
<ul>
<li><a href="#3-5-1"> How to build the plugin on Unix/Linux
</a>
<li><a href="#3-5-2"> How to build the plugin on Windows
</a>
</ul>
</ul>
<li><a href="#4"> Troubleshooting
</a>
<li><a href="#5"> How to write your own database driver
</a>
</ul>
<!-- endtoc -->
<p> <a name="Introduction"></a>
<h2> Introduction
</h2>
<a name="1"></a><p> The <a href="sql.html">SQL Module</a> uses driver <a href="plugins-howto.html">plugins</a> in order to communicate with different database APIs.
Since the SQL Module API is database-independent, all
database-specific code is contained within these drivers. Several
drivers are supplied with Qt and other drivers can be added. The
driver source code is supplied and can be used as a model for <a href="#development">writing your own drivers</a>.
<p> To build a driver plugin you need the client API that is
shipped with every DBMS (Database Management System). Most
installation programs also allow you to install "development
libraries", and these are what you need. These libraries are
responsible for the low-level communication with the DBMS.
<p> The currently available drivers shipped with Qt are:
<ul>
<li> <a href="#QMYSQL3">QMYSQL3</a> - MySQL Driver
<li> <a href="#QOCI8">QOCI8</a> - Oracle Call Interface Driver
<li> <a href="#QODBC3">QODBC3</a> - ODBC (Open Database Connectivity) Driver
<li> <a href="#QPSQL7">QPSQL7</a> - PostgreSQL v6.x and v7.x Driver
<li> <a href="#QTDS7">QTDS7</a> - Sybase Adaptive Server and Microsoft SQL Server Driver
</ul>
<p> Note that not all of the plugins are shipped with the Qt Free Edition
due to licence incompatibilities with the GPL.
<p> <h2> Building the drivers using configure
</h2>
<a name="2"></a><p> The Qt configure script automatically detects the available client
libraries on your machine. Run "configure -help" to see what drivers
may be built. You should get an output similar to this:
<p> <pre>
Possible values for <driver>: [ mysql oci odbc psql tds ]
Auto-Detected on this system: [ mysql psql ]
</pre>
<p> Note that configure cannot detect the neccessary libraries and include
files if they are not in the standard paths, so it may be necessary to
specify these paths using the "-I" and "-L" switches. If your MySQL
include files are installed in /usr/local/mysql (or in C:\mysql\include
on Windows), then pass the following parameter to configure:
"-I/usr/local/mysql" (or "-IC:\mysql\include" for Windows).
<p> Note that on Windows the parameter -I doesn't allow spaces in filenames,
so use the 8.3 name instead, i.e. use "C:\progra~1\mysql" instead of
"C:\program files\mysql".
<p> Use the <tt>-qt-sql-<driver></tt> parameter to build the database driver statically
into your Qt library or <tt>-plugin-sql-<driver></tt> to build the driver as a
plugin. Look at the chapters below for additional information about required
libraries.
<p> <h2> Building the plugins manually
</h2>
<a name="3"></a><p> <a name="QMYSQL3"></a>
<h3> QMYSQL3 - MySQL 3.x
</h3>
<a name="3-1"></a><p> <!-- index QMYSQL3 --><a name="QMYSQL3"></a>
<p> <h4> General informations
</h4>
<a name="3-1-1"></a><p> MySQL 3.x doesn't support SQL transactions by default. There are some backends
which offer this functionality. Recent versions of the MySQL client
libraries (>3.23.34) allow you to use transactions on those modified servers.
<p> If you have a recent client library and connect to a transaction-enabled MySQL
server, a call to the <a href="qsqldriver.html#hasFeature">QSqlDriver::hasFeature</a>( QSqlDriver::Transactions )
function returns TRUE and SQL transactions can be used.
<p> You can find information about MySQL on <a href="http://www.mysql.com">http://www.mysql.com</a>
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-1-2"></a><p> You need the MySQL header files and as well as the shared library
"libmysqlclient.so". Depending on your Linux distribution you need to
install a package which is usually called "mysql-devel".
<p> Tell qmake where to find the MySQL header files and shared libraries
(here it is assumed that MySQL is installed in /usr/local) and run make:
<p> <pre>
cd $QTDIR/plugins/src/sqldrivers/mysql
qmake -o Makefile "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient" mysql.pro
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-1-3"></a><p> You need to get the MySQL installation files. Run SETUP.EXE and
choose "Custom Install". Install the "Libs & Include Files" Module.
Build the plugin as follows (here it is assumed that MySQL is
installed in C:\MYSQL):
<p> <pre>
cd %QTDIR%\plugins\src\sqldrivers\mysql
qmake -o Makefile "INCLUDEPATH+=C:\MYSQL\INCLUDE" "LIBS+=C:\MYSQL\LIB\OPT\LIBMYSQL.LIB" mysql.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace "nmake" with "make" in the
statement above.
<p> <a name="QOCI8"></a>
<h3> QOCI8 - Oracle Call Interface
</h3>
<a name="3-2"></a><p> <!-- index QOCI8 --><a name="QOCI8"></a>
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-2-1"></a><p> All files required to build driver should ship with the standard Oracle
install. For Linux, it may be possible to copy headers from another
platform's install.
<p> Oracle library files required to build driver:
<p> <ul>
<li> libclntsh.so
<li> libclntsh.so.8.0
<li> libwtc8.so
</ul>
<p> Oracle header files required to build driver:
<p> <ul>
<li> nzerror.h
<li> nzt.h
<li> oci.h
<li> oci1.h
<li> oci8dp.h
<li> ociap.h
<li> ociapr.h
<li> ocidef.h
<li> ocidem.h
<li> ocidfn.h
<li> ociextp.h
<li> ocikp.h
<li> ocikpr.h
<li> odci.h
<li> oratypes.h
<li> ori.h
<li> orid.h
<li> orl.h
<li> oro.h
<li> ort.h
</ul>
<p> Tell qmake where to find the Oracle header files and shared libraries
(here it is assumed that Oracle is installed in /usr/local) and run make:
<p> <pre>
cd $QTDIR/plugins/src/sqldrivers/oci
qmake -o Makefile "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lclntsh -lwtc8" oci.pro
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-2-2"></a><p> Choosing the option "Programmer" in the Oracle Client Installer from
the Oracle Client Installation CD is sufficient to build the plugin.
<p> Build the plugin as follows (here it is assumed that Oracle Client is
installed in C:\oracle):
<p> <pre>
cd %QTDIR%\plugins\src\sqldrivers\oci
qmake -o Makefile "INCLUDEPATH+=C:\oracle\oci\include" oci.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace "nmake" with "make" in the
statement above.
<p> <a name="QODBC3"></a>
<h3> QODBC3 - Open Database Connectivity
</h3>
<a name="3-3"></a><p> <!-- index QODBC3 --><a name="QODBC3"></a>
<p> <h4> General informations
</h4>
<a name="3-3-1"></a><p> ODBC (Open Database Connectivity) is a general interface that allows you
to connect to multiple DBMS using a common interface. The QODBC3 driver
allows you to connect to an ODBC driver manager and access his datasources.
Note that you also need to install and configure ODBC drivers for the
ODBC driver manager that is installed on your system. The QODBC3 plugin
then allows you to use these data sources in your Qt project.
<p> On Windows systems after 95 an ODBC driver manager should be installed
by default, for Unix systems there are some implementations which have to
be installed first. Note that every client that uses your application
is required to have an ODBC driver manager installed, otherwise the
QODBC3 plugin will not work.
<p> The QODBC3 Plugin needs an ODBC compilant driver manager version 2.0 or
greater to work. Some ODBC drivers claim to be version 2.0 compilant,
but do not offer all needed functionality. The QODBC3 plugin therefore
checks whether the data source can be used after a connection has been
established and refuses to work if the check fails. If you don't
like this behaviour, you can remove the <tt>#define ODBC_CHECK_DRIVER</tt>
line from the file <tt>qsql_odbc.cpp</tt>. Do this at your own risk!
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-3-2"></a><p> It is recommended that you use unixODBC. You can find the newest
version and ODBC drivers at <a href="http://www.unixodbc.org">http://www.unixodbc.org</a>.
You need the unixODBC header files and shared libraries.
<p> Tell qmake where to find the unixODBC header files and shared libraries
(here it is assumed that unixODBC is installed in /usr/local/unixODBC)
and run make:
<p> <pre>
cd $QTDIR/plugins/src/sqldrivers/odbc
qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc"
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-3-3"></a><p> The ODBC header and include files should already be installed in the
right directories. You just have to build the plugin as follows:
<p> <pre>
cd %QTDIR%\plugins\src\sqldrivers\odbc
qmake -o Makefile odbc.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace "nmake" with "make" in the
statement above.
<p> <a name="QPSQL7"></a>
<h3> QPSQL7 - PostgreSQL version 6 and 7
</h3>
<a name="3-4"></a><p> <!-- index QPSQL7 --><a name="QPSQL7"></a>
<p> <h4> General information
</h4>
<a name="3-4-1"></a><p> The QPSQL7 driver supports both version 6 and 7 of PostgreSQL. We recommend
compiling the plugin with a recent version of the PostgreSQL Client API (libpq)
because it is more stable and still downward compatible.
<p> If you want to link the plugin against the libpq shipped with version 6 we
recomment a recent version like PostgreSQL 6.5.3, otherwise a connection to a
version 7 server may not work.
<p> The driver auto-detects the server version of PostgreSQL after a connection was
successful. If the server is too old or the version information cannot be determined
a warning is issued.
<p> For more information about PostgreSQL visit <a href="http://www.postgresql.org">http://www.postgresql.org</a>.
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-4-2"></a><p> Just installing "libpq.so" and the corresponding header files is
unfortunately not sufficient. You have to get the whole source
distribution and run the configure script once (there is no need
to build it if you have already installed a binary distribution).
<p> Tell qmake where to find the PostgreSQL header files and shared
libraries (here it is assumed that you extracted the PostgreSQL
source code in /usr/src/psql and the shared library is installed
in /usr/lib) and run make:
<p> <pre>
cd $QTDIR/plugins/src/sqldrivers/psql
qmake -o Makefile "INCLUDEPATH+=/usr/src/psql/src/include /usr/src/psql/src/interfaces/libpq" "LIBS+=-L/usr/lib -lpq" psql.pro
make
</pre>
<p> <a name="QTDS7"></a>
<h3> QTDS7 - Sybase Adaptive Server and Microsoft SQL Server
</h3>
<a name="3-5"></a><p> <!-- index QTDS7 --><a name="QTDS7"></a>
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-5-1"></a><p> Under Unix, two libraries are available which support the TDS protocol:
<p> - FreeTDS, a free implementation of the TDS protocol ( <a href="http://www.freetds.org">http://www.freetds.org</a> ).
Note that FreeTDS is not yet stable, so some functionality may not work
as expected.
<p> - Sybase Open Client, available from <a href="http://www.sybase.com">http://www.sybase.com</a>
Note for Linux users: Get the Open Client RPM from <a href="http://linux.sybase.com">http://linux.sybase.com</a>
<p> Regardless of which library you use, the shared object file "libsybdb.so" is needed.
Set the SYBASE environment variable to point to the directory where you
installed the client library and execute qmake:
<p> <pre>
cd $QTDIR/plugins/src/sqldrivers/tds
qmake -o Makefile "INCLUDEPATH=$SYBASE/include" "LIBS=-L$SYBASE/lib -lsybdb"
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-5-2"></a><p> You can either use the DB-Library supplied by Microsoft or the Sybase Open Client
( <a href="http://www.sybase.com">http://www.sybase.com</a> ). You have to include NTWDBLIB.LIB
to build the plugin:
<p> <pre>
cd %QTDIR%\plugins\src\sqldrivers\tds
qmake -o Makefile "LIBS+=NTWDBLIB.LIB" tds.pro
nmake
</pre>
<p> By default the Microsoft library is used on Windows, if you want to force
the use of the Sybase Open Client, you have to define
Q_USE_SYBASE in %QTDIR%\src\sql\drivers\tds\qsql_tds.cpp.
<p> <a name="troubleshooting"></a>
<h2> Troubleshooting
</h2>
<a name="4"></a><p> You should always use client libraries that have been compiled with the same
compiler as you are using for your project. If you cannot get a source distibution
to compile the client libraries yourself, you have to make sure that the
pre-compiled library is compatible with your compiler, otherwise you will get
a lot of "undefined symbols" errors. Some compilers have tools to convert libraries,
e.g. Borland ships the tool <tt>COFF2OMF.EXE</tt> to convert libraries that
have been generated with Microsoft Visual C++.
<p> If the compilation of a plugin succeeds but it cannot be loaded,
make sure that the following requirements are met:
<p> <ul>
<li> Make sure you are using a shared Qt library, you cannot use the
plugins with a static build.
<li> Make sure that the environment variable QTDIR points to the right
directory. Go to the $QTDIR/plugins/sqldrivers directory and make sure
that the plugin exists in that directory.
<li> Make sure that the client libraries of the DBMS are available on the
system. On Unix, run the command <tt>ldd</tt> and pass the name of the
plugin as parameter, for example <tt>ldd libqsqlmysql.so</tt>. You will
get a warning if any of the client libraries couldn't be found.
On Windows, you can use the dependency walker of Visual Studio.
</ul>
<p> <a name="development"></a>
<h2> How to write your own database driver
</h2>
<a name="5"></a><p> <a href="qsqldatabase.html">QSqlDatabase</a> is responsible for loading and managing database driver
plugins. When a database is added (see <a href="qsqldatabase.html#addDatabase">QSqlDatabase::addDatabase</a>()),
the appropriate driver plugin is loaded (using <a href="qsqldriverplugin.html">QSqlDriverPlugin</a>).
QSqlDatabase relies on the driver plugin to provide interfaces for
<a href="qsqldriver.html">QSqlDriver</a> and <a href="qsqlresult.html">QSqlResult</a>.
<p> QSqlDriver is an abstract base class which defines the functionality
of a SQL database driver. This includes functions such as
<a href="qsqldriver.html#open">QSqlDriver::open</a>() and <a href="qsqldriver.html#close">QSqlDriver::close</a>(). QSqlDriver is responsible
for connecting to a database, establish the proper environment, etc.
In addition, QSqlDriver can create <a href="qsqlquery.html">QSqlQuery</a> objects appropriate for
the particular database API. QSqlDatabase forwards many of its
function calls directly to QSqlDriver which provides the concrete
implementation.
<p> QSqlResult is an abstract base class which defines the functionality
of a SQL database query. This includes statements such as SELECT,
UPDATE, or ALTER TABLE. QSqlResult contains functions such as
QSqlResult::next() and QSqlResult::value(). QSqlResult is responsible
for sending queries to the database, returning result data, etc.
QSqlQuery forwards many of its function calls directly to <a href="qsqlresult.html">QSqlResult</a>
which provides the concrete implementation.
<p> <a href="qsqldriver.html">QSqlDriver</a> and QSqlResult are closely connected. When implementing a
Qt SQL driver, both of these classes must to be subclassed and the
abstract virtual methods in each class must be implemented.
<p> To implement a Qt SQL driver as a plugin (so that it is recognized and
loaded by the Qt library at runtime), the driver must use the
Q_EXPORT_PLUGIN macro. Please read the <a href="plugins-howto.html">Qt
Plugin</a> documentation for more information on this. You can
also check out how this is done in the SQL plugins that is provided
with Qt in <tt>QTDIR/plugins/src/sqldrivers</tt> and <tt>QTDIR/src/sql/drivers</tt>.
<p>
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media
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by-pkgid
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