QSqlDatabase: QMYSQL driver not loaded

[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'

Help Please!!!

[SGaist]

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