QMYSQL driver not loaded but available

[RedTales]

I am trying to connect my Qt application with MySQL, and am getting the (notorious, it seems) QMSQL driver not loaded but available error. I have done research and read a number of possible solutions for this problem, but it seems as though there are a number of solutions and I am somewhat confused on what avenue to pursue for my particular case.

I am using Qt 5.7.0 and Ubuntu 16.04.

Here is my code to connect to the db:


db = QSqlDatabase::addDatabase("QMYSQL");
db.setHostName("host");
db.setUserName("name");
db.setPassword("password");
db.setDatabaseName("dbName");
bool ok = db.open();

Results of locate mysqlclient in terminal



locate mysqlclient

/home/seth/libmysqlclient-dev_5.7.20-1ubuntu17.04_amd64.deb
/home/seth/libmysqlclient20_5.7.20-1ubuntu17.04_amd64.deb
/usr/lib/x86_64-linux-gnu/libmysqlclient.so.20
/usr/lib/x86_64-linux-gnu/libmysqlclient.so.20.3.7
/usr/share/doc/libmysqlclient20
/usr/share/doc/libmysqlclient20/COPYING.gz
/usr/share/doc/libmysqlclient20/README
/usr/share/doc/libmysqlclient20/changelog.Debian.gz
/usr/share/doc/libmysqlclient20/copyright
/usr/share/lintian/overrides/libmysqlclient20
/var/cache/apt/archives/libmysqlclient20_5.7.20-1ubuntu16.04_amd64.deb
/var/lib/dpkg/info/libmysqlclient20:amd64.list
/var/lib/dpkg/info/libmysqlclient20:amd64.md5sums
/var/lib/dpkg/info/libmysqlclient20:amd64.shlibs
/var/lib/dpkg/info/libmysqlclient20:amd64.triggers

Results of ldd on sqldrivers



ldd QTDIR/plugins/sqldrivers

linux-vdso.so.1 => (0x00007fffcf9d9000)
libmysqlclient_r.so.16 => not found
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fab4c4c9000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007fab4c290000)
libnsl.so.1 => /lib/x86_64-linux-gnu/libnsl.so.1 (0x00007fab4c077000)
libssl.so.10 => not found
libcrypto.so.10 => not found
libQt5Sql.so.5 => /home/seth/Qt5.7.0/5.7/gcc_64/plugins/sqldrivers/./../../lib/libQt5Sql.so.5 (0x00007fab4be31000)
libQt5Core.so.5 => /home/seth/Qt5.7.0/5.7/gcc_64/plugins/sqldrivers/./../../lib/libQt5Core.so.5 (0x00007fab4b716000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fab4b4f8000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fab4b176000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fab4ae6d000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fab4ac56000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fab4a88c000)
libicui18n.so.56 => /home/seth/Qt5.7.0/5.7/gcc_64/plugins/sqldrivers/./../../lib/libicui18n.so.56 (0x00007fab4a3f2000)
libicuuc.so.56 => /home/seth/Qt5.7.0/5.7/gcc_64/plugins/sqldrivers/./../../lib/libicuuc.so.56 (0x00007fab4a039000)
libicudata.so.56 => /home/seth/Qt5.7.0/5.7/gcc_64/plugins/sqldrivers/./../../lib/libicudata.so.56 (0x00007fab48656000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fab48452000)
libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fab4824f000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fab48047000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fab47d36000)
/lib64/ld-linux-x86-64.so.2 (0x00005576b7572000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fab47ac5000)

I believe line 2 above is the problem. So my question is essentially, how to I fix the libmysqlclient_r.so.16 => not found error?

[ChrisW67]

Your second listing is not the result of the command at line 1. I assume you executed ldd on {QTDIR}/qt5/plugins/sqldrivers/libqsqlmysql.so.

The Qt Mysql plugin for your Qt version has been built against an older Mysql client. You need to either:

Install an older Mysql client (libmysqlclient16 at a guess). The deb pacakge in /home/seth are from a later Ubuntu version, but the 16.04 xenial packages are also API version 20.
Build the Qt Mysql plugin from source matching your Qt version. You will need the relevant Mysql dev packages matching the client you have.

Given that you seem to have your own local Qt 5.7 the second option may be easiest.

The missing libcrypto and libssl are from OpenSSL.