QMYSQL - Ubuntu 18.04.1

mbyrd777

Sorry if I'm an idiot. I'm having issues using the MySQL features in qt.

Getting an error on a project:

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

Here's the output of ldd

~/Qt/5.11.2/gcc_64/plugins/sqldrivers$ ldd libqsqlmysql.so
	linux-vdso.so.1 (0x00007ffc87f8b000)
	libQt5Sql.so.5 => /home/matthew/Qt/5.11.2/gcc_64/plugins/sqldrivers/./../../lib/libQt5Sql.so.5 (0x00007f746fd5a000)
	libQt5Core.so.5 => /home/matthew/Qt/5.11.2/gcc_64/plugins/sqldrivers/./../../lib/libQt5Core.so.5 (0x00007f746f600000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f746f3e1000)
	libmysqlclient.so.18 => not found
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f746f058000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f746ecba000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f746eaa2000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f746e6b1000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f746e494000)
	libicui18n.so.56 => /home/matthew/Qt/5.11.2/gcc_64/plugins/sqldrivers/./../../lib/libicui18n.so.56 (0x00007f746dffb000)
	libicuuc.so.56 => /home/matthew/Qt/5.11.2/gcc_64/plugins/sqldrivers/./../../lib/libicuuc.so.56 (0x00007f746dc43000)
	libicudata.so.56 => /home/matthew/Qt/5.11.2/gcc_64/plugins/sqldrivers/./../../lib/libicudata.so.56 (0x00007f746c260000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f746c05c000)
	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f746be5a000)
	libglib-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f746bb44000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f74701b5000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f746b8d2000)

I'm wondering if it is a version mismatch for the client libraries and I'm too ignorant to fix it? I do have these files.

/usr/lib/x86_64-linux-gnu/libmysqlclient.so.20
/usr/lib/x86_64-linux-gnu/libmysqlclient.so.20.3.11

Thanks in advance to anyone that can help.

mrjj

@mbyrd777
Hi and welcome to the forums.

It seems it tried to load the
libmysqlclient.so.18
but yours is named
libmysqlclient.so.20

You could try to make a sym link from the
libmysqlclient.so.18 ( as name ) to libmysqlclient.so.20

ln -sf /usr/lib/libmysqlclient.so.20 /usr/lib/libmysqlclient.so.18

CHECK the man page. im known to always switch target and the sym name.

i cant promise it will work but there is a good chance its compatible.
If not, its just a link, so should not blow up anything. (much)

mbyrd777

@mrjj That's sort of what I was thinking but I didn't want to cause any sort of unintended consequences and didn't know if there was an official way to handle library differences. Thanks for the tip

edit: the symlink didn't seem to work as the same error occurred.

mrjj

@mbyrd777
Hi
Well I have done that with various other libs and had no ill side effects as
its sort of just makes an alias for the lib.
However, it it really wants the .18 version, the app might crash but
the link can easy be removed so i find the risk very small for anything bad system wise.

Update:
ok. thats odd. I recall a case where it look in the "wrong"/other folder
/lib/x86_64 and not in /usr/lib/

Im not super linux experct so lets wait some hours, some of the others mods are very into
linux :)

mbyrd777

@mrjj For this release of Ubuntu it has the libraries here:

/usr/lib/x86_64-linux-gnu/

I don't even know where to look to see where qt is trying to access the libraries from

kshegunov

@mbyrd777 said in QMYSQL - Ubuntu 18.04.1:

Sorry if I'm an idiot.

You're not. :)

I'm wondering if it is a version mismatch for the client libraries and I'm too ignorant to fix it? I do have these files.

It is a version mismatch. You need to provide the correct library for the plugin. Did you build Qt yourself?
Most painless would be to just install the correct client library from the repo though.

mbyrd777

@kshegunov I downloaded the community edition installer today and ran it to install 5.11.2
I didn't build from source

kshegunov

Okay, I suggest you install libmysqlclient18 from the repo, which should fix your problem.

mbyrd777

@kshegunov said in QMYSQL - Ubuntu 18.04.1:

libmysqlclient18

$ sudo apt-get install libmysqlclient18
[sudo] password for matthew: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package libmysqlclient18 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'libmysqlclient18' has no installation candidate

kshegunov

https://packages.ubuntu.com/search?keywords=libmysqlclient&searchon=names&suite=trusty&section=all

I don't pretend to understand the Ubuntu release cycle, as I work on debian. However as I see it, you have to pin the trusty repositories with a low priority in the apt configuration, and then you can install it.

JonB

@mbyrd777
Let's start a little bit from scratch here.

Why do you want/need any kind of "libmysqlclient18", I mean the 18 instead of the 20?

I installed Ubuntu 18.04 from fresh yesterday. Everything default. I get all my Qt/MySQL stuff from the repo, with standard apt-get (e.g. apt-get install qt5-default). I do not get source code or compile anything.

Mine works fine, without any issues. I have no "libmysqlclient18" anywhere. I have libmysqlclient.so.20 (libmysqlclient.so.20.3.11 actually).

Now, the point is, if anything my Qt/MySQL will be older than yours (e.g. it's Qt 5.9.5), and yet I'm up to libmysqlclient.so.20. So where does your need for 18 come from?

P.S.
I notice I did a apt-get install libqt5sql5-mysql. Do you do that one?

kshegunov

@JonB said in QMYSQL - Ubuntu 18.04.1:

Why do you want/need any kind of "libmysqlclient18", I mean the 18 instead of the 20?

Because the plugin he got from the installer is built against that version.

I get all my Qt/MySQL stuff from the repo

I do too, however it's not the case here.

I have libmysqlclient.so.20 (libmysqlclient.so.20.3.11 actually).

Thanks to the maintainers of your distro, they take the time to repackage the binaries appropriately and set the correct dependencies, so you (and I) get it out of the box.

JonB · I have libmysqlclient.so.20 (libmysqlclient.so.20.3.11 actually).

@kshegunov

Because the plugin he got from the installer is built against that version.
I didn't get that bit. What installer does he talk about in his question?

Oh, do you mean in a later post I just noticed:

@kshegunov I downloaded the community edition installer today and ran it to install 5.11.2

Anyway, if it has to be like that. I was just mentioning that if he could manage/do as I have I get all the stuff he mentions just with the apt-gets and do not have his issue. Or he can fiddle potentially for days till he sorts out his current situation. It was just a heads-up.

kshegunov

@JonB said in QMYSQL - Ubuntu 18.04.1:

Oh, do you mean in a later post I just noticed

Indeed.

Anyway, if it has to be like that. I was just mentioning that if he could manage/do as I have I get all the stuff he mentions just with the apt-gets and do not have his issue. Or he can fiddle potentially for days till he sorts out his current situation. It was just a heads-up.

When I'm not needing a Qt build myself (like trying a patch or something) I personally do it just like you described.