Embedded MySQL server

[SebastianS]

Hey guy, does somebody have experience in setting up an embedded MySQL server with Qt and can show some code how its done?

[NetZwerg]

As far as I understood you just link to the libmysqld and start it by calling mysql_library_init() (end it before application exit with mysql_library_end()). For every thread that likes to access any mysql-function (so any QSql* function) call the corresponding thread init mysql_thread_init() (and mysql_thread_end()).

The rest should behave as it has been with a default mysql server.

[SebastianS]

I tried this code from the MySQL reference but it crashes when it comes to the point mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");. Does somebody has a working exmaple for a embedded server?

#include <mysql.h>

static char *server_options[] = {"mysql_test", "--defaults-file=my.ini", NULL};
int num_elements = (sizeof(server_options) / sizeof(char *)) - 1;
static char *server_groups[] = {"libmysqld_server", "libmysqld_client", NULL};

int main(int argc, char *argv[])
{
    QSqlDatabase mydb;
    MYSQL *mysql;

    mysql_library_init(num_elements, server_options, server_groups);
    mysql = mysql_init(NULL);
    mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");
    mysql_options(mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);

    mysql_real_connect(mysql, NULL, NULL, NULL, "database1", 0, NULL, 0);

    mydb = QSqlDatabase::addDatabase("QMYSQL", "con1");

    mydb.setDatabaseName("database1");

    if(!mydb.open())
    {
        qDebug() << mydb.lastError();
    }

    mysql_library_end();
    return 0;
}

[SebastianS]

Is really nobody out there who got this working?

[mrjj]

Hi

Seems that not that many try the MYSQL embedded.
Even on
http://stackoverflow.com/questions/16990142/qt-c-embedded-mysql
No ones answers.

And you did link with the libmysqld ?

[SebastianS]

Hi,

Yes I did. As I figured out using the embedded server doesn't make sense anyway in my application as it is multithreaded and the embedded server supports only one connection at a time. I don't mark it as solved since I am never the less interested how this works out.

[mrjj]

@SebastianS
Ok.
Strange it would just crash then.
mysql_init did return "im happy" etc?

Well multi threaded could still work using a semaphore to control write access but
if you need concurrent access its of no use.

Sadly I think the question will just slowly drift to other pages and no one will ever see it again.

[SGaist]

Hi,

AFAIK, you don't have to fiddle with raw MySQL c++ calls. You should be able to use Qt the exact same way as you would with a classic client server setup

[Andre_Xavier]

Note on https://dev.mysql.com/doc/refman/5.7/en/libmysqld.html says: “The libmysqld embedded server library is deprecated as of MySQL 5.7.17 and will be removed in MySQL 8.0.“