QSqlDatabase: QMYSQL driver not loaded / Build MySQL Plugin

bionegative

Thank you, i manage to build the driver on one of my develop machines. However when i am doing the same on my other Linux machine it doesnt list it as an avaible driver even?
[Qt run]
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC3 QODBC

~/Qt5.5.0/5.5/gcc_64/plugins/sqldrivers$ ls -l
-rwxr-xr-x 1 user user 73368 okt 9 06:48 libqsqlmysql.so
» shows its been newly built

ldd libqsqlmysql.so
libmysqlclient.so.18 => /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18 (0x00007f6565b28000)
» It have found the link

» It seems like Qt dosnt know about it afterall.
usualy qt's output list the driver atleast but doesnt show it as loaded untill its compiled.

Edit: I tried load it during runtime
[Qt]
QPluginLoader loader;
loader.load("TheFullFilePath");
loader.errorString();
» And it shows me this error: "The file '/home/..........libqsqlmysql.so' is not a valid Qt plugin.
So something when wrong during building.

FIXED:
» This error was kinda fun, there was a manually added path variable in qtcreator->Tools->Options->Build & Run->[Tab]Qt Versons. Where the Auto-detected where right and the Manual was pointing at an old qt4 version.
After deleting that and rebuild the driver it worked..

Malhar

Hi ,
i am facing a different kind of issue. after doing ldd to libqsqlmysql.so inside sqldrivers folder am unable to see
libmysqlclient_r.so.16 => not found this particular statement.
Please help and reply ASAP.

Thanks

SGaist

Hi and welcome to devnet,

Then, what do you see ?

Malhar

@SGaist After doing ldd libqmysqlclint.so got this

ldd libqsqlpsql.so
linux-vdso.so.1 => (0x00007ffd58adb000)
libpq.so.5 => /usr/lib/libpq.so.5 (0x00007f8a75afe000)
libQt5Sql.so.5 => /opt/Qt5.1.0/5.1.0/gcc_64/plugins/sqldrivers/./../../lib/libQt5Sql.so.5 (0x00007f8a758bf000)
libQt5Core.so.5 => /opt/Qt5.1.0/5.1.0/gcc_64/plugins/sqldrivers/./../../lib/libQt5Core.so.5 (0x00007f8a75236000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8a74f32000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8a74b6d000)
libssl.so.1.0.0 => /lib/x86_64-linux-gnu/libssl.so.1.0.0 (0x00007f8a7490e000)
libcrypto.so.1.0.0 => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 (0x00007f8a74533000)
libkrb5.so.3 => /usr/lib/x86_64-linux-gnu/libkrb5.so.3 (0x00007f8a74268000)
libcom_err.so.2 => /lib/x86_64-linux-gnu/libcom_err.so.2 (0x00007f8a74064000)
libgssapi_krb5.so.2 => /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2 (0x00007f8a73e1e000)
libldap_r-2.4.so.2 => /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2 (0x00007f8a73bcd000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8a739af000)
libicui18n.so.51 => /opt/Qt5.1.0/5.1.0/gcc_64/plugins/sqldrivers/./../../lib/libicui18n.so.51 (0x00007f8a73596000)
libicuuc.so.51 => /opt/Qt5.1.0/5.1.0/gcc_64/plugins/sqldrivers/./../../lib/libicuuc.so.51 (0x00007f8a73210000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8a7300c000)
libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f8a72e0a000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8a72c02000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f8a728fa000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8a725f4000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8a723de000)
/lib64/ld-linux-x86-64.so.2 (0x00007f8a75f42000)
libk5crypto.so.3 => /usr/lib/x86_64-linux-gnu/libk5crypto.so.3 (0x00007f8a721af000)
libkrb5support.so.0 => /usr/lib/x86_64-linux-gnu/libkrb5support.so.0 (0x00007f8a71fa4000)
libkeyutils.so.1 => /lib/x86_64-linux-gnu/libkeyutils.so.1 (0x00007f8a71da0000)
libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007f8a71b85000)
liblber-2.4.so.2 => /usr/lib/x86_64-linux-gnu/liblber-2.4.so.2 (0x00007f8a71976000)
libsasl2.so.2 => /usr/lib/x86_64-linux-gnu/libsasl2.so.2 (0x00007f8a7175b000)
libgssapi.so.3 => /usr/lib/x86_64-linux-gnu/libgssapi.so.3 (0x00007f8a7151d000)
libgnutls.so.26 => /usr/lib/x86_64-linux-gnu/libgnutls.so.26 (0x00007f8a7125f000)
libgcrypt.so.11 => /lib/x86_64-linux-gnu/libgcrypt.so.11 (0x00007f8a70fdf000)
libicudata.so.51 => /opt/Qt5.1.0/5.1.0/gcc_64/plugins/sqldrivers/./../../lib/libicudata.so.51 (0x00007f8a6f896000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f8a6f658000)
libheimntlm.so.0 => /usr/lib/x86_64-linux-gnu/libheimntlm.so.0 (0x00007f8a6f44f000)
libkrb5.so.26 => /usr/lib/x86_64-linux-gnu/libkrb5.so.26 (0x00007f8a6f1c7000)
libasn1.so.8 => /usr/lib/x86_64-linux-gnu/libasn1.so.8 (0x00007f8a6ef26000)
libhcrypto.so.4 => /usr/lib/x86_64-linux-gnu/libhcrypto.so.4 (0x00007f8a6ecf3000)
libroken.so.18 => /usr/lib/x86_64-linux-gnu/libroken.so.18 (0x00007f8a6eade000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8a6e8c5000)
libtasn1.so.6 => /usr/lib/x86_64-linux-gnu/libtasn1.so.6 (0x00007f8a6e6b1000)
libp11-kit.so.0 => /usr/lib/x86_64-linux-gnu/libp11-kit.so.0 (0x00007f8a6e46f000)
libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f8a6e26a000)
libwind.so.0 => /usr/lib/x86_64-linux-gnu/libwind.so.0 (0x00007f8a6e041000)
libheimbase.so.1 => /usr/lib/x86_64-linux-gnu/libheimbase.so.1 (0x00007f8a6de33000)
libhx509.so.5 => /usr/lib/x86_64-linux-gnu/libhx509.so.5 (0x00007f8a6dbea000)
libsqlite3.so.0 => /usr/lib/x86_64-linux-gnu/libsqlite3.so.0 (0x00007f8a6d931000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f8a6d6f8000)
libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007f8a6d4f0000)

Malhar

@SGaist sorry man that was my mistake i did ldd to a different .so file.

Thanks

Peter Van Grieken

@mattewre: really good post! Tnx!
@SGaist: I've been reading the forums and noticed you've been answering a lot of question asked by beginners like me. Thank you for the support!!

This post really helped to understand this issue, but I've been trying to tackle the same problem for a few days now but for some reason I don't seem to be able to recompile the library "libqsqlmysql.so".

What I can see

Compiling an application that uses mysql produces this output:

loaded library "/home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so"
QLibraryPrivate::loadPlugin failed on "/home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so" : "Cannot load library /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so: (libmysqlclient_r.so.16: cannot open shared object file: No such file or directory)"
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7

library:

I do have the file libmysqlclient_r.so.18 located in /usr/lib/
(note: I also have libmysqlclient_r.so.18.3.0 located in /usr/lib/ so during my frantic search for a solution I may have updated mysql again :-) ). I guess recompiling libqsqlmysql.so will link to the correct one?

doublechecking library dependency

petervg@ubuntu:~/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers$ ldd libqsqlmysql.so
linux-vdso.so.1 => (0x00007ffc493bf000)
libmysqlclient_r.so.16 => not found
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f5ffbe74000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f5ffbc3b000)
libnsl.so.1 => /lib/x86_64-linux-gnu/libnsl.so.1 (0x00007f5ffba21000)
libssl.so.10 => not found
libcrypto.so.10 => not found
libQt5Sql.so.5 => /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/./../../lib/libQt5Sql.so.5 (0x00007f5ffb7e0000)
libQt5Core.so.5 => /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/./../../lib/libQt5Core.so.5 (0x00007f5ffb09a000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f5ffae7b000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f5ffaaf9000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f5ffa7f1000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f5ffa5d9000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f5ffa20f000)
libicui18n.so.54 => /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/./../../lib/libicui18n.so.54 (0x00007f5ff9da0000)
libicuuc.so.54 => /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/./../../lib/libicuuc.so.54 (0x00007f5ff99f2000)
libicudata.so.54 => /home/petervg/Qt5.5.1/5.5/gcc_64/plugins/sqldrivers/./../../lib/libicudata.so.54 (0x00007f5ff7fc8000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f5ff7dc4000)
libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f5ff7bc1000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f5ff79b9000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f5ff76aa000)
/lib64/ld-linux-x86-64.so.2 (0x00005569bd500000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f5ff743c000)

try to recompile libqsqlmysql.so from the source included with the offline installer.

petervg@ubuntu:~/Qt5.5.1/5.5/Src/qtbase/src/plugins/sqldrivers/mysql$ qmake
petervg@ubuntu:~/Qt5.5.1/5.5/Src/qtbase/src/plugins/sqldrivers/mysql$ make
rm -f libqsqlmysql.so
g++ -Wl,--no-undefined -Wl,-O1 -Wl,--enable-new-dtags -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64 -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64 -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64/lib -shared -o libqsqlmysql.so .obj/main.o .obj/qsql_mysql.o .obj/moc_qsql_mysql_p.o -rdynamic -L/usr/lib64/mysql -lz -lcrypt -lnsl -lm -lssl -lcrypto -L/home/petervg/Qt5.5.1/5.5/Src/qtbase/lib -lQt5Sql -L/usr/local/lib -lmysqlclient_r -lQt5Core -lpthread
/usr/bin/ld: cannot find -lQt5Sql
/usr/bin/ld: cannot find -lQt5Core
collect2: error: ld returned 1 exit status
Makefile:142: recipe for target '../../../../plugins/sqldrivers/libqsqlmysql.so' failed
make: *** [../../../../plugins/sqldrivers/libqsqlmysql.so] Error 1
petervg@ubuntu:~/Qt5.5.1/5.5/Src/qtbase/src/plugins/sqldrivers/mysql$

-> I'm not sure if this is relevant, but I can see the library Qt5Sql cannot be found even though in (1) i can see the library libQt5Sql.so.5 is found in /home/petervg/Qt5.5.1/5.5/gcc_64/lib.

try to recompile libqsqlmysql.so from the source I downloaded (qt-everywhere-opensource-src-5.5.1).

petervg@ubuntu:~/Downloads/qt-everywhere-opensource-src-5.5.1/qtbase/src/plugins/sqldrivers/mysql$ qmake
petervg@ubuntu:~/Downloads/qt-everywhere-opensource-src-5.5.1/qtbase/src/plugins/sqldrivers/mysql$ make
rm -f libqsqlmysql.so
g++ -Wl,--no-undefined -Wl,-O1 -Wl,--enable-new-dtags -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64 -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64 -Wl,-rpath,/home/petervg/Qt5.5.1/5.5/gcc_64/lib -shared -o libqsqlmysql.so .obj/main.o .obj/qsql_mysql.o .obj/moc_qsql_mysql_p.o -rdynamic -L/usr/lib64/mysql -lmysqlclient_r -lz -lcrypt -lnsl -lm -lssl -lcrypto -L/home/petervg/Downloads/qt-everywhere-opensource-src-5.5.1/qtbase/lib -lQt5Sql -lQt5Core -lpthread
/usr/bin/ld: cannot find -lQt5Sql
/usr/bin/ld: cannot find -lQt5Core
collect2: error: ld returned 1 exit status
Makefile:142: recipe for target '../../../../plugins/sqldrivers/libqsqlmysql.so' failed
make: *** [../../../../plugins/sqldrivers/libqsqlmysql.so] Error 1

-> identical results...

Conclusion

I've learned it's best to first make sure you have the latest mysql files installed before installing QT, so i guess I could completely reinstall Qt now, but I'ld like to learn what I have been doing wrong....

Any tips where I should look further?

With kind regards
Peter

Peter Van Grieken

(answering myself :-) )

i open the mysql.pro in qtcreator (Coming from windows... I like an ide a lot more than the command line... sorry :-) ) and I added folowing line to this file:

LIBS += -L/home/petervg/Qt5.5.1/5.5/gcc_64/lib

I did this because I knew libQt5Sql.so.5 was located in /home/petervg/Qt5.5.1/5.5/gcc_64/lib.

What I do need to look into, is WHY this works? In /etc/environment I added:

"PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/home/petervg/Qt5.5.1/Tools/QtCreator/bin/:/home/petervg/Qt5.5.1/5.5/gcc_64/lib:/home/petervg/Qt5.5.1/Tools/QtCreator/lib/qtcreator:/usr/lib"/x86_64-linux-gnu"

and in /home/petervg/.profile I added:

LIBRARY_PATH="/home/petervg/Qt5.5.1/5.5/gcc_64/lib:/home/petervg/Qt5.5.1/5.5/gcc_64/plugins:/usr/lib/x86_64-linux-gnu:$LIBRARY_PATH"
LD_LIBRARY_PATH="/home/petervg/Qt5.5.1/5.5/gcc_64/lib:/home/petervg/Qt5.5.1/5.5/gcc_64/plugins:/usr/lib/x86_64-linux-gnu:$LD_LIBRARY_PATH"
export LIBRARY_PATH
export LD_LIBRARY_PATH

Neither of these solutions worked.

But my problem us finally solved, so up to the next one... If anybody could shed some light as to why adding the line in the .PRO file worked, but not when adding the path to the environment variables... I'll be glad to know...

Tnx!

SGaist

Hi,

The most simple way to ensure you're using the right qmake is to call it with the full path to the executable. One other problem comes from the fact that you also have Qt Creator's stuff in your PATH. Don't do it, Qt Creator comes with it's own build of Qt so that it's a complete autonomous application.

The LIBS += -L/path/ tells the linker where to look for libraries.

Peter Van Grieken

Thanks!

I'll take a good look at the PATH variable.

SGaist

Leave it clean, that way you ensure that you're not mixing things on your system while building the driver.

RalfSchaefer

Hi,

i'm facing a similiar sort of problem, not completely solvable by the steps above.
I recompiled the QMYSQL-plugin and it's linked to the correct mysql-libraries.
After doing ldd /opt/Qt/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so I got this:

ldd /opt/Qt/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so 
       linux-vdso.so.1 (0x00007fffd7d83000)
       libmysqlclient.so.18 => /usr/lib64/libmysqlclient.so.18 (0x00007f9eb8607000)
        libz.so.1 => /lib64/libz.so.1 (0x00007f9eb83f0000)
        libcrypt.so.1 => /lib64/libcrypt.so.1 (0x00007f9eb81b5000)
        libnsl.so.1 => /lib64/libnsl.so.1 (0x00007f9eb7f9d000)
        libssl.so.1.0.0 => /lib64/libssl.so.1.0.0 (0x00007f9eb7d34000)
        libcrypto.so.1.0.0 => /lib64/libcrypto.so.1.0.0 (0x00007f9eb7941000)
        libQt5Sql.so.5 => /opt/Qt/5.5/gcc_64/lib/libQt5Sql.so.5 (0x00007f9eb7701000)
        libQt5Core.so.5 => /opt/Qt/5.5/gcc_64/lib/libQt5Core.so.5 (0x00007f9eb6fba000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f9eb6d9d000)
        libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00007f9eb6a1b000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f9eb6719000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f9eb6502000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f9eb615b000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f9eb5f56000)
        libicui18n.so.54 => /opt/Qt/5.5/gcc_64/lib/libicui18n.so.54 (0x00007f9eb5ae8000)
        libicuuc.so.54 => /opt/Qt/5.5/gcc_64/lib/libicuuc.so.54 (0x00007f9eb5739000)
        libicudata.so.54 => /opt/Qt/5.5/gcc_64/lib/libicudata.so.54 (0x00007f9eb3d0f000)
        libgthread-2.0.so.0 => /usr/lib64/libgthread-2.0.so.0 (0x00007f9eb3b0d000)
        librt.so.1 => /lib64/librt.so.1 (0x00007f9eb3904000)
        libglib-2.0.so.0 => /usr/lib64/libglib-2.0.so.0 (0x00007f9eb35f5000)
        /lib64/ld-linux-x86-64.so.2 (0x000055fc1f3d8000)
        libpcre.so.1 => /usr/lib64/libpcre.so.1 (0x00007f9eb338e000)

So, erverything looks fine here.

When I try to connect to the database, it still doesn't work. It seems, QSqlDatabase loads the plugin without problems, setting dabase specific stuff fails.

My code-snippet, containing additional debug-stuff:

    QPluginLoader loader;
    loader.setFileName("/opt/Qt/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so");
    qDebug() << "PluginLoader worked =" << loader.load();
    qDebug() << "Plugin Loader error=" << loader.errorString();

    QStringList driverlist =QSqlDatabase::drivers();
    qDebug() << "Databases: ";
    for (int i = 0; i < driverlist.size(); ++i)
    {
        qDebug() << driverlist.at(i);
    }

    if (!db_opened)
    {
            db = new QSqlDatabase();
            qDebug() << "Step 1 - Database:    is valid=" << db->isValid();
            db->addDatabase("QMYSQL3","cooptimedb");
            qDebug() << "Step 2 - Database:    is valid=" << db->isValid();

            db->setHostName("localhost");
            db->setDatabaseName("cooptime");
            db->setUserName("cooptime");
            db->setPassword("...");
            db->setPort(3306);

            qDebug() << "Database\n========\nHostname: " << db->hostName() << "\nDatabasename: " << db->databaseName() << "\nUsername: " << db->userName() << "\nPassword: " << db->password()  << "\nPort: " << db->port();


            if (! db->open())
            {
                qDebug() << "db errorcode=" <<  db->lastError().nativeErrorCode();
                qDebug() << "db errormessage=" << db->lastError() .text();
            }

The output of the code above is:

PluginLoader worked = true
Plugin Loader error= "Unknown error"
Databases: 
"QSQLITE"
"QMYSQL"
"QMYSQL3"
"QPSQL"
"QPSQL7"
Step 1 - Database:    is valid= false
Step 2 - Database:    is valid= false
Database
========
Hostname:  "" 
Databasename:  "" 
Username:  "" 
Password:  "" 
Port:  -1
db errorcode= ""
db errormessage= "Driver not loaded Driver not loaded"

So it seems, the driver still doesn't load.

Any help would be very appreciated. Thanks in advance.

SGaist

Hi and welcome to devnet,

Your code is wrong, you are creating an invalid QSqlDatabase object on the heap and then you call a static function on it.

Please take a look at QSqlDatabase's detailed documentation. There's an example there on how to do the setup and connection.

RalfSchaefer

@SGaist Thanks for your help!! That's it. Now all works fine for me!

fikou1335

Hi SGaist,

I have a new problem with QMysql, everything worked fine since today, actually when I executede this line

    DB = QSqlDatabase::addDatabase( "QMYSQL");

I have this error

libgcc_s.so.1 must be installed for pthread_cancel to work

I don't know why,

the plugin is correctly compiled without error, and using the ldd he found the libgcc_s.so.1

Can you help me please!

SGaist

Hi and welcome to devnet,

Which architecture are on ?

fikou1335

Hi and thanks for your quick response

I m working on Ubuntu 64bits
i got this

Precision-M4600:/usr/local/Trolltech/Qt-4.8.6/plugins/sqldrivers$ ldd libqsqlmysql.so 	linux-vdso.so.1 =>  (0x00007ffceb314000)
	libmysqlclient.so.18 => /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18 (0x00007f7a884c6000)
	libQtSql.so.4 => /usr/local/Trolltech/Qt-4.8.6/lib/libQtSql.so.4 (0x00007f7a88285000)
	libQtCore.so.4 => /usr/local/Trolltech/Qt-4.8.6/lib/libQtCore.so.4 (0x00007f7a87d91000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f7a87a7f000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f7a87868000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7a874a3000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f7a8728a000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f7a87086000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f7a86e68000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f7a86b62000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f7a8695a000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f7a88c10000)

and this

Precision-M4600:/usr/lib/x86_64-linux-gnu$ ldd libmysqlclient.so.18
	linux-vdso.so.1 =>  (0x00007ffe50bc0000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fe8f4940000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fe8f473c000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fe8f451e000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fe8f4218000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe8f3e53000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fe8f5091000)

If I comment the addBase line in my code everything works fine without connecting to the Database of course.
when I try to list the drivers using

QStringList driverlist =QSqlDatabase::drivers();

I got this

Databases: QSQLITE QMYSQL3 QMYSQL

Everything works fine Monday, I checked the database, I could write on it fine,, but yesterday, it crash my application
hope it can help!

fikou1335

I have just created a new app with the main function and it works and connect fine to my database.

In my code I comment all the last code that I added this week and SURPRISE it works as well.
the problem is probably due to a third library that i started to use this week. I ll check why it cause a crach to mysql o_O

SGaist

What new library did you add ?

fikou1335

This one Dahua SDK

You can check by yourslef, they have a source example, PTZControl that works fine, but try to add

      DB = QSqlDatabase::addDatabase( "QMYSQL");

and you should get the same error.

this sdk is used to control PTZ cams of Dahua brand.
I changed my code by creating a new app to control cameras and get the informations of position from my big application.

put this main instsead of it

#include <QtGui/QApplication>
#include "dialog.h"
#include <QTextCodec>
#include <QObject>
#include <QtSql/QSqlDatabase>
#include <QStringList>
#include <QtSql/QSqlQuery>
#include <QtSql/QSqlRecord>
#include <QVariant>
#include <iostream>



int main(int argc, char *argv[])
{
    QSqlDatabase DB;
    cout <<endl<< "try connect MYSQL "<< endl;
    try
    {
        DB = QSqlDatabase::addDatabase( "QMYSQL");
    }
    catch(...)
    {
        cout << "fatal error"<< endl;
    }
    cout << "add database"<< endl;
    DB.setDatabaseName( "intrusiondetection" );
    DB.setUserName( "root" );

    DB.setPassword( "root" );
    cout << "1"<< endl;

    DB.setHostName( "" );

    cout << "try to connect"<< endl;
    if (DB.open())
    {
        cout << "QMYSQL correctly connected "<< endl;
    }
    else
    {
        cout << "QMYSQL not connected "<< endl;
    }


    QApplication a(argc, argv);
    QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));
    Dialog w;
    w.show();

    return a.exec();
}

tell me if you got the same error.?

SGaist

One thing that you should first correct: move the database initialization code after the QApplication object creation.