Russian Qt Forum

MySQL Embedded Server

This is a useful way of providing a stand-alone application that incorporates a database server. As noted above, the embedded server libraries seem to have disappeared from the MySQL 5 releases, so you will need to go back to MySQL 4 or compile MySQL 5 from source with the embedded server option. To keep it simple, obtain the "Windows (x86) ZIP/Setup.EXE" package for MySQL 4.1.22 and install only the Developer Components.

Locate the libmysqld.lib file in c:\mysql\Embedded\DLL\release and make the conversion of the library file to the GNU compatible form:

# cd c:\mysql\Embedded\DLL\release
# reimp -d libmysqld.lib
# dlltool -k --input-def libmysqld.def --dllname libmysqld.dll --output-lib libmysqld.a

Change the code in the source file c:\qt\src\sql\drivers\mysql\qsql_mysql.cpp to the lines below (this is near the bottom of the file) since the mysql_get_client_version() function call appears to have changed or disappeared from the MySQL API.

//#if MYSQL_VERSION_ID >= 40108
// d->preparedQuerysEnabled = mysql_get_client_version() >= 40108
// && mysql_get_server_version(d->mysql) >= 40100;
//#else
// d->preparedQuerysEnabled = false;
//#endif
d->preparedQuerysEnabled = true;

At the top of this file is a section that needs to be commented out as follows:

//#ifdef Q_OS_WIN32
// comment the next line out if you want to use MySQL/embedded on Win32 systems.
// note that it will crash if you don't statically link to the mysql/e library!
//# define Q_NO_MYSQL_EMBEDDED
//#endif

The advice is to be taken seriously. We will need to statically link the libmysqld.a file. If MySQL server is to be incorporated into an application, then it is likely that Qt would also be statically compiled with the application, as Qt is not common in the Windows world.

Now do the following for static compilation of Qt and MySQL Embedded:

# cd c:\qt
# mingw32-make clean
# configure -debug-and-release -static -qt-sql-mysql -l mysqld -I c:\mysql\include -L c:\mysql\embedded\dll\release
# mingw32-make sub-src

The third option -l specifies the libmysqld.a library to use, the second (capital i) specifies the directory of the MySQL include files and the final -L specifies the directory of the MySQL library file. The make sub-src line ensures that the examples are not built. This not only cuts down the compilation time, but also the disk space as each example is built with the full Qt static linkage.

This compiles without errors, but I have not yet attempted to compile an application to make use of the embedded MySQL server.

Кстати какую версию MySQL собирал

The MySQL embedded server is a drop-in replacement for the normal client library. With the embedded MySQL server, a MySQL server is not required to use MySQL functionality.

To use the embedded MySQL server, simply link the Qt plugin to libmysqld instead of libmysqlclient. This can be done by replacing -lmysqlclient_r by -lmysqld in the qmake command in the section below.

//#ifdef Q_OS_WIN32
// comment the next line out if you want to use MySQL/embedded on Win32 systems.
// note that it will crash if you don't statically link to the mysql/e library!
//# define Q_NO_MYSQL_EMBEDDED
//#endif

[embedded]
skip-bdb
skip-innodb
skip-ndbcluster
#skip-networking
skip-grant-tables

[project_embedded_SERVER]
port=3307

basedir=e:/opt/project/trunk
datadir=e:/opt/project/trunk/data
tmpdir=d:/windows/temp

default-character-set=cp1251
default-collation=cp1251_general_ci
character_sets-dir=e:/opt/project/trunk/share/charsets/

static void qLibraryInit()
{
#ifndef Q_NO_MYSQL_EMBEDDED
# if MYSQL_VERSION_ID >= 40000
    if (qMySqlInitHandledByUser || qMySqlConnectionCount > 1)
        return;

static char *server_args[] = {
    "project_embedded_SERVER",
    "--defaults-file=e:/opt/project/trunk/my.cnf",
    "--key_buffer_size=32M"
};
static char *server_groups[] = {
    "embedded",
    "server",
    "project_embedded_SERVER",
    (char *)NULL
};

# if (MYSQL_VERSION_ID >= 40110 && MYSQL_VERSION_ID < 50000) || MYSQL_VERSION_ID >= 50003
    if (mysql_library_init(sizeof(server_args) / sizeof(char *), server_args, server_groups)) {
# else
    if (mysql_server_init(sizeof(server_args) / sizeof(char *), server_args, server_groups)) {
# endif
        qWarning("QMYSQLDriver::qServerInit: unable to start server.");
    }
# endif // MYSQL_VERSION_ID
#endif // Q_NO_MYSQL_EMBEDDED
}

QSqlDatabase::addDatabase("QMYSQL");

if (mysql_library_init(sizeof(server_args) / sizeof(char *), server_args, server_groups)) {

Program received signal SIGSEGV, Segmentation fault.

0x7c918fea in ntdll!RtlpWaitForCriticalSection () from D:\WINDOWS\system32\ntdll.dll

if (mysql_library_init(sizeof(server_args) / sizeof(char *), server_args, server_groups)) {

if (mysql_library_init(0, 0, 0)) {

так-с...для меня тема закрыта!
если ещё кто хочет для себя её закрыть, рисуем пиво и стучимся к крокусу в приват :)

зы. мускули в своём проспекте не наврали - падения производительности я пока не наблюдаю