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Building the MySQL driver for Qt4/MinGW
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Versions used: Qt4.0.0 / MinGW 3.4.2 / MySQL 4.1

1) Creating the MySQL client library.
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Unfortunatly, the client libraries (libmysql.ddl and libmysql.lib)
shipped with MySQL are compiled with the M$ compiler and are causing
problems with try to link them with the MinGW compiler. Therefore,
we first need to create a MinGW compatible library out of libmysql.dll.
This can be done by taking the following steps:

# cd c:\mysql\lib\opt (c:\mysql is where our MySQL is installed)
# reimp -d libmysql.lib (reimp comes with MinGW utilities)
# dlltool -k --input-def libmysql.def --dllname libmysql.dll --output-lib
libmysql.a

Now we have the MinGW compatible library called libmysql.a

2) Building the QMYSQL plugin dll.
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Now we can build the Qt MySQL plugin based on the above MinGW compatible
library. This can be done by taking the following steps:

# cd c:\qt\src\plugins\sqldrivers\mysql (c:\qt is where qt is installed)
# qmake -o Makefile "INCLUDEPATH+=C:\MYSQL\INCLUDE"
"LIBS+=-LC:\MYSQL\LIB\OPT -lmysql" mysql.pro
# make (will build and install the plugin)

There is no need to change the mysql.pro file, because the -lmysql option
that is passed to the LIBS args, will disable the win32 section in the
mysql.pro

win32 {
!contains(LIBS, .*mysql.*) { # Returns false, so libmysql.lib will
not
LIBS *= libmysql.lib # be added.
}
}

3) libmysql.dll
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When you have build your qt application using the QMYSQL plugin, you have to
make
sure that libmysql.dll is in your path, or is resides next to your
executable.
Otherwise, the database open() call will fail with "Driver not loaded" in
the
SQLError return object.