4. QSqlDatabase: QMYSQL driver not loaded

QSqlDatabase: QMYSQL driver not loaded


  • I run ubuntu 14.04 and i installed Qt4 and Qt5. I have created and implemented a project in Qt5 ( specifically : Based on Qt 5.4.1 (GCC 4.6.1, 32 bit) ).

    I try in my programm to make connection to a database ( ΜySql ) but I can not.

    When I run this code:

    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("myTEST_db");
    db.setUserName("root");
    db.setPassword("123456789");
    if (!db.open())
    {
      QMessageBox::critical(0, QObject::tr("Database Error"),
                db.lastError().text());
    }

    I get this error :

    QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7

    When i run this code :

        QPluginLoader loader;
    loader.setFileName("/home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so");
    qDebug() << "PluginLoader worked =" << loader.load();
    qDebug() << "Plugin Loader error=" << loader.errorString();

    qDebug() << QCoreApplication::libraryPaths();
    QCoreApplication::addLibraryPath("/home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so");
    qDebug() << QSqlDatabase::drivers();

    I get this error :

    PluginLoader worked = false
Plugin Loader error= "Cannot load library /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so: (libmysqlclient_r.so.16: cannot open shared object file: No such file or directory)"
("/home/myuser/Qt/5.4/gcc/plugins", "/home/myuser/Qt TestProject/build-TestProject-Desktop_Qt_5_4_1_GCC_32bit-Debug")
("QSQLITE", "QPSQL", "QPSQL7")

    I can not understand what is happening, please very much you can help me?
    I stress that I have installed and QT4 (maybe somewhere confused).

    Thank you in advance.

    0
  • Qt Champions 2018

    Did you check that /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so really exists? Is it 32bit?
    One note: if you add a directory to library path then do not pass the file name! It must be a directory.

    0 1 Reply

  • @jsulm Firstly thank you very much friend for so prompt reply.
    Yes I have 32-bit.

    As for the file:

    ls Qt/5.4/gcc/plugins/sqldrivers/
libqsqlite.so  libqsqlmysql.so  libqsqlpsql.so

    one more effort:

        qDebug() << QCoreApplication::libraryPaths();
    QCoreApplication::addLibraryPath("/home/myuser/Qt/5.4/gcc/plugins/sqldrivers/");
    qDebug() << QSqlDatabase::drivers();


    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("myTEST_db");
    db.setUserName("root");
    db.setPassword("123456789");
    if (!db.open())
    {
      QMessageBox::critical(0, QObject::tr("Database Error"),
                db.lastError().text());

    Error :

    ("/home/myuser/Qt/5.4/gcc/plugins", "/home/myuser/Qt TestProject/build-TestProject-Desktop_Qt_5_4_1_GCC_32bit-Debug")
("QSQLITE", "QMYSQL", "QMYSQL3", "QPSQL", "QPSQL7")
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7
    0
  • Lifetime Qt Champion

    Hi,

    Do you have the MySQL client libraries installed on your system ?

    0 1 Reply

  • @SGaist If i do not do wrong , yes.
    Extra now again I ran :

    sudo apt-get install mysql-client
sudo apt-get install libmysqlclient-dev
sudo apt-get install libqt5sql5-mysql
sudo apt-get install libmysqlclient16-dev
sudo apt-get install libmysql++-dev

    Because I despaired, that I have found of libraries i have installing.

    But absolutely nothing. I did not expect to be so hard. :(

    0
  • Lifetime Qt Champion

    Can you run ldd on Qt's MySQL plugin ?

    0 2 Replies

  • @SGaist
    this is what you mean;

    :~/Qt/5.4/gcc/plugins/sqldrivers$ ldd libqsqlmysql.so
	linux-gate.so.1 =>  (0xb76e3000)
	libmysqlclient_r.so.16 => not found
	libQt5Sql.so.5 => /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/./../../lib/libQt5Sql.so.5 (0xb7672000)
	libQt5Core.so.5 => /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/./../../lib/libQt5Core.so.5 (0xb712d000)
	libstdc++.so.6 => /usr/lib/i386-linux-gnu/libstdc++.so.6 (0xb702b000)
	libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xb6e7d000)
	libpthread.so.0 => /lib/i386-linux-gnu/libpthread.so.0 (0xb6e61000)
	libicui18n.so.53 => /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/./../../lib/libicui18n.so.53 (0xb6c0a000)
	libicuuc.so.53 => /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/./../../lib/libicuuc.so.53 (0xb6a8a000)
	libdl.so.2 => /lib/i386-linux-gnu/libdl.so.2 (0xb6a85000)
	libgthread-2.0.so.0 => /usr/lib/i386-linux-gnu/libgthread-2.0.so.0 (0xb6a82000)
	librt.so.1 => /lib/i386-linux-gnu/librt.so.1 (0xb6a79000)
	libglib-2.0.so.0 => /lib/i386-linux-gnu/libglib-2.0.so.0 (0xb696d000)
	libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xb6926000)
	libgcc_s.so.1 => /lib/i386-linux-gnu/libgcc_s.so.1 (0xb6908000)
	/lib/ld-linux.so.2 (0xb76e4000)
	libicudata.so.53 => /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/./../../lib/libicudata.so.53 (0xb547f000)
	libpcre.so.3 => /lib/i386-linux-gnu/libpcre.so.3 (0xb5441000)

    I entered the forum to tell you , this problem have just i found. xaxa and I see that what you ask (if i do not do wrong)

    0
  • Qt Champions 2018

    That's probably the problem:
    libmysqlclient_r.so.16 => not found

    It looks like the MySQL lib is not installed.

    0

  • what can I do to fix it?

    0
  • Qt Champions 2018

    Can you check whether you have libmysqlclient_r.so.16 on your system?
    On my Ubuntu 14.04 it is libmysqlclient_r.so.18

    0 1 Reply

  • @jsulm
    Yes I have the same too :

    :/usr/lib/i386-linux-gnu$ ls | grep libmysql
libmysqlclient.a
libmysqlclient_r.a
libmysqlclient_r.so
libmysqlclient_r.so.18
libmysqlclient_r.so.18.0.0
libmysqlclient.so
libmysqlclient.so.18
libmysqlclient.so.18.0.0
    0
  • Lifetime Qt Champion

    Then the easiest way is to rebuild the plugin against your installed MySQL client libraries. It's described here

    0 1 Reply

  • @SGaist
    Could someone please guide me?
    This guide does not help that much.. :/

    There is no other way?

    0

  • Hi, you could try to trick Qt you've got the correct file, by using the newer version as the older one (just a guess :-):
    cp libmysqlclient_r.so.18.0.0 libmysqlclient_r.so.16

    0 1 Reply

  • @hskoglund
    I tried to shortcut and copy as you say now.
    but the same effect :

    code :

        QPluginLoader loader;
    loader.setFileName("/home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so");
    qDebug() << "PluginLoader worked =" << loader.load();
    qDebug() << "Plugin Loader error=" << loader.errorString();

    error :

    PluginLoader worked = false
Plugin Loader error= "Cannot load library /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so: (/usr/lib/i386-linux-gnu/libmysqlclient_r.so.16: version `libmysqlclient_16' not found (required by /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so))"
    0

  • Ok, maybe you need to go further tricking Qt also that the libmysqlclient.so.16 is fine and well, by also copying that file:
    cp libmysqlclient.so.18.0.0 libmysqlclient.so.16

    0 1 Reply

  • @hskoglund
    oops you're right! I had not noticed the name. But now? I have this error :

    PluginLoader worked = false
Plugin Loader error= "Cannot load library /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so: (/usr/lib/i386-linux-gnu/libmysqlclient_r.so.16: version `libmysqlclient_16' not found (required by /home/myuser/Qt/5.4/gcc/plugins/sqldrivers/libqsqlmysql.so))"

    and these files :

    :/usr/lib/i386-linux-gnu$ ls | grep libmysql
libmysqlclient.a
libmysqlclient_r.a
libmysqlclient_r.so
libmysqlclient_r.so.16
libmysqlclient_r.so.18
libmysqlclient_r.so.18.0.0
libmysqlclient.so
libmysqlclient.so.16
libmysqlclient.so.18
libmysqlclient.so.18.0.0
    0

  • Ahhh, sorry it seems the ruse didn't work all the way :-(
    It's probably a version resource or something simular in the libmysqlclient.so.18.0.0 file that says "version 18" and not "version 16".

    Anyway I think your next step is instead to try to download and install the kosher *.16, have you tried?
    sudo apt-get install libmysqlclient16

    0
  • Lifetime Qt Champion

    You can't cheat like that on Linux ;)

    @Tas-sos what trouble did you have to rebuild the plugin ? It's really just grab Qt's source and follow the lines of the documentation.

    0 1 Reply

  • @hskoglund

    Never mind my friend anyway thank you very much!
    Yes I have tried it and got this:

    E: Unable to locate the package libmysqlclient16

    or this :

    E: Unable to locate the package libmysqlclient16-dev

    @SGaist
    xaxaax my friend like your answer.
    "You can't cheat like that on Linux ;)"

    As for the guide (documentation) , basically confuses me a little and I do not know if I can follow him because for example he says to run this command :

    cd $QTDIR/qtbase/src/plugins/sqldrivers/mysql

    But me the file structure is :

    :~$ ls Qt 
5.4
components.xml
Docs
Examples
Extras
InstallationLog.txt
Licenses
MaintenanceTool
MaintenanceTool.dat
MaintenanceTool.ini
network.xml
Tools

    :~/Qt/5.4$ ls
android_armv7  gcc

    :~/Qt/5.4/gcc$ ls
bin
icudtl.dat
imports
include
lib
libexec
mkspecs
phrasebooks
plugins
qml
qtwebengine_resources.pak
translations

    :~/Qt/5.4/gcc/plugins$ ls -l

audio
bearer
designer
generic
geoservices
iconengines
imageformats
mediaservice
platforminputcontexts
platforms
platformthemes
playlistformats
position
printsupport
qml1tooling
qmltooling
qtwebengine
sensorgestures
sensors
sqldrivers  <-----------

    :~/Qt/5.4/gcc/plugins$ tree sqldrivers/
sqldrivers/
├── libqsqlite.so
├── libqsqlmysql.so
└── libqsqlpsql.so

    the path that says, to me (as you see) does not exist. :/
    Extra searches:

    find  ~/Qt -name "sqldrivers"
/home/myuser/Qt/Tools/QtCreator/bin/plugins/sqldrivers
/home/myuser/Qt/5.4/gcc/plugins/sqldrivers

    $find  ~/Qt -name "qtbase"
-nothing-

    $ find  ~/Qt -name "mysql"
-nothing-

    In my system the folders with name "mysql" are only those :

    sudo find  / -name "mysql"
/var/lib/mysql
/var/lib/mysql/mysql
/var/log/mysql
/etc/apparmor.d/abstractions/mysql
/etc/init.d/mysql
/etc/mysql
/usr/bin/mysql
/usr/lib/perl5/auto/DBD/mysql
/usr/lib/perl5/DBD/mysql
/usr/lib/mysql
/usr/share/maven-repo/mysql
/usr/share/mysql
/usr/share/bash-completion/completions/mysql
/usr/include/mysql
/usr/include/mysql/mysql

    and folder named "qtbase" does not exist.
    For this reason the documentation does not help.

    0
  • Lifetime Qt Champion

    That's because you don't have the Qt sources installed. Use maintenancetool to download them.

    1 2 Replies

  • @SGaist
    Unbelievable though it was in front of me I had no idea about the "maintenancetool". I am inexperienced with using Qt not know so much about this, but I hope now to learn.

    I ran as you said the "MaintenanceTool" located in the "Qt" folder and i installed the "sources".
    Then I have what I needed! :D

    The guide now is satisfactory and effective. ;)

    Simply the guide says this path:

    cd $QTDIR/qtbase/src/plugins/sqldrivers/mysql

    to me is this:

    /home/myuser/Qt/5.4/Src/qtbase/src/plugins/sqldrivers/mysql

    Then because I have and version "Qt4" this command:

    qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" mysql.pro

    i run in this way:

    /home/myuser/Qt/5.4/gcc/bin/qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" mysql.pro

    All now work perfectly! I'm very happy about that! I Struggled a lot with this issue and does not need nor expecting.
    Thank you very very much my friends! I am indebted to your with your efficient and fast help!

    THANK YOU!

    0 2 Replies

  • This post is deleted!
    0

  • @SGaist said in QSqlDatabase: QMYSQL driver not loaded:

    That's because you don't have the Qt sources installed. Use maintenancetool to download them.

    Can someone tell please me what are QT sources..

    0
  • Lifetime Qt Champion

    Hi,

    As silly as it may sound: that's the sources of the Qt library.

    0

  • This post is deleted!
    0

  • @SGaist @Tas-sos Im just Right where you are, usgin make... put i have this error:
    'MySql Lib is Not Defined'

    0_1558483350957_f0fa2c95-6be7-4055-8355-c23fad355ed9-image.png

    Help Please!!!

    0
  • Lifetime Qt Champion

    @Gualtix Hi and welcome to devnet, you are not following the current documented procedure.

    1
ubuntu 14.04 40 qsqldatabase 35 qmysql 16 driver not load 4
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