QSqlDatabase: QMYSQL driver not loaded

Tas-sos

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.

jsulm

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.

Tas-sos

@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

SGaist

Hi,

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

Tas-sos

@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. :(

SGaist

Can you run ldd on Qt's MySQL plugin ?

Tas-sos

@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)

jsulm

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

It looks like the MySQL lib is not installed.

Tas-sos

what can I do to fix it?

jsulm

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

Tas-sos

@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

SGaist

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

Tas-sos

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

There is no other way?

hskoglund

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

Tas-sos

@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))"

hskoglund

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

Tas-sos

@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

hskoglund

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

SGaist

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.

Tas-sos

@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.

SGaist

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

Tas-sos

@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!

chawila

This post is deleted!

chawila

@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..

SGaist

Hi,

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

chawila

This post is deleted!

Gualtix

@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!!!

SGaist

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

Important: Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

QSqlDatabase: QMYSQL driver not loaded