Issues with QMYSQL driver on Windows/MariaDB

ael16

So I need to get another version of libmysql.dll which is compiled with MinGW? I found these instructions:


1) Creating the MySQL client library.

Unfortunatly, the client libraries (libmysql.ddl and libmysql.lib) shipped with MySQL are compiled with the M$ compiler and are causing problems with try to link them with the MinGW compiler. Therefore, we first need to create a MinGW compatible library out of libmysql.dll. This can be done by taking the following steps:
1.cd c:\mysql\lib\opt    (c:\mysql is where our MySQL is installed)
2.reimp -d libmysql.lib  (reimp comes with MinGW utilities)
3.dlltool -k –input-def libmysql.def –dllname libmysql.dll –output-lib libmysql.a

(http://zhucongqi.cn/blog/2012-04-19-building-the-mysql-driver-for-qt4(mingw)/)

dlltool is included in C:\Qt\Tools\mingw492_32\bin. But reimp is missing although it seems to say it should be included with MinGW.

ael16

I tried to compile the source code but it failed with this message:
"In file included from main.cpp:36:0:
../../../sql/drivers/mysql/qsql_mysql_p.h:55:19: fatal error: mysql.h: No such file or directory
#include <mysql.h>"

But I do have the file mysql.h:
C:\Program Files\MariaDB 10.1\include\mysql>dir mysql.h
...
2015-11-20 18:08 39 069 mysql.h
...

And I Included the path with:
qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include" "LIBS+=C:\Program Files\MariaDB 10.1\lib\libmysql.lib" mysql.pro

I also tried qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include\mysql", and / and two \ instead of one backslash.

Can you see what could be wrong here?

C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include" "LIBS+=C:\Program Fil
es\MariaDB 10.1\lib\libmysql.lib" mysql.pro

C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>mingw32-make.exe
mingw32-make.exe -f Makefile.Release all
mingw32-make.exe[1]: Entering directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
g++ -c -pipe -fno-keep-inline-dllexport -O2 -std=c++1y -fno-exceptions -frtti -Wall -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_N
O_CAST_FROM_ASCII -DQT_NO_EXCEPTIONS -DQT_NO_DEBUG -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -IC:/utils/postgresql/pgsql/include
-IC:/utils/my_sql/my_sql/include -IC:/openssl/include -IC:\Program -IFiles\MariaDB -I10.1\include -IC:\Qt\5.6\mingw49_32\include\Q
tSql\5.6.1 -IC:\Qt\5.6\mingw49_32\include\QtSql\5.6.1\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore\5.6.1 -IC:\Qt\5.6\mingw49_32\inc
lude\QtCore\5.6.1\QtCore -IC:\Qt\5.6\mingw49_32\include -IC:\Qt\5.6\mingw49_32\include\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore
 -I.moc\release -I..\..\..\..\mkspecs\win32-g++  -o .obj\release\main.o main.cpp
In file included from main.cpp:36:0:
../../../sql/drivers/mysql/qsql_mysql_p.h:55:19: fatal error: mysql.h: No such file or directory
 #include <mysql.h>
                   ^
compilation terminated.
Makefile.Release:468: recipe for target '.obj/release/main.o' failed
mingw32-make.exe[1]: *** [.obj/release/main.o] Error 1
mingw32-make.exe[1]: Leaving directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
makefile:38: recipe for target 'release-all' failed
mingw32-make.exe: *** [release-all] Error 2

SGaist

Windows and paths with spaces don't mix well for development. You should rather install MariaDB in a path without any space. That will save you a whole lot of trouble.

ael16

I tried with QODBC and this worked! Because I reinstalled Qt I got QODBC which wasn't in the previous version, I think. Followed these instructions to first install DSN from MySQL (32 bit, the 64 bit seemed not to work).

http://stackoverflow.com/questions/25165525/how-to-connect-to-a-mysql-database-through-odbc-from-qt-application

    QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
    db.setDatabaseName("Driver={MySQL ODBC 5.3 Unicode Driver};DATABASE=dbname;");
    db.setUserName("root");
    db.setPassword("mypassword");

Unless I can get the QMYSQL to work this may be an acceptable workaround. Perhaps if someone else has problem with QMYSQL they could try with QODBC from the new Qt version.

Hamed.Masafi

@ael16 said:

I tried to compile the source code but it failed with this message:
"In file included from main.cpp:36:0:
../../../sql/drivers/mysql/qsql_mysql_p.h:55:19: fatal error: mysql.h: No such file or directory
#include <mysql.h>"

But I do have the file mysql.h:
C:\Program Files\MariaDB 10.1\include\mysql>dir mysql.h
...
2015-11-20 18:08 39 069 mysql.h
...

And I Included the path with:
qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include" "LIBS+=C:\Program Files\MariaDB 10.1\lib\libmysql.lib" mysql.pro

I also tried qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include\mysql", and / and two \ instead of one backslash.

Can you see what could be wrong here?

C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>qmake "INCLUDEPATH+=C:\Program Files\MariaDB 10.1\include" "LIBS+=C:\Program Fil
es\MariaDB 10.1\lib\libmysql.lib" mysql.pro

C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>mingw32-make.exe
mingw32-make.exe -f Makefile.Release all
mingw32-make.exe[1]: Entering directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
g++ -c -pipe -fno-keep-inline-dllexport -O2 -std=c++1y -fno-exceptions -frtti -Wall -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_N
O_CAST_FROM_ASCII -DQT_NO_EXCEPTIONS -DQT_NO_DEBUG -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -IC:/utils/postgresql/pgsql/include
-IC:/utils/my_sql/my_sql/include -IC:/openssl/include -IC:\Program -IFiles\MariaDB -I10.1\include -IC:\Qt\5.6\mingw49_32\include\Q
tSql\5.6.1 -IC:\Qt\5.6\mingw49_32\include\QtSql\5.6.1\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore\5.6.1 -IC:\Qt\5.6\mingw49_32\inc
lude\QtCore\5.6.1\QtCore -IC:\Qt\5.6\mingw49_32\include -IC:\Qt\5.6\mingw49_32\include\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore
 -I.moc\release -I..\..\..\..\mkspecs\win32-g++  -o .obj\release\main.o main.cpp
In file included from main.cpp:36:0:
../../../sql/drivers/mysql/qsql_mysql_p.h:55:19: fatal error: mysql.h: No such file or directory
 #include <mysql.h>
                   ^
compilation terminated.
Makefile.Release:468: recipe for target '.obj/release/main.o' failed
mingw32-make.exe[1]: *** [.obj/release/main.o] Error 1
mingw32-make.exe[1]: Leaving directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
makefile:38: recipe for target 'release-all' failed
mingw32-make.exe: *** [release-all] Error 2

Change it to below and re-test:

#include <mysql/mysql.h>"

SGaist

@ael16, sorry, I misread your setup.

As @Hamed-Masafi indirectly pointed, your INCLUDEPATH statement doesn't include the mysql folder under include. That's why the header wasn't found in the first place.

But still, the recommendation about spaces in path holds for Windows, it's usually at link time that the trouble begins.

ael16

@Hamed.Masafi

Unfortunately it didn't help.

I changed C:\Qt\5.6\Src\qtbase\src\sql\drivers\mysql\qsql_mysql_p.h to #include <mysql/mysql.h>

Then qmake:
C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>qmake "INCLUDEPATH+=C:/Program Files/MariaDB 10.1/include" "LIBS+=C:/Program Files/MariaDB 10.1/lib/libmysql.lib" mysql.pro

Now my Makefile has this row:
$(QMAKE) "INCLUDEPATH+=C:/Program Files/MariaDB 10.1/include" "LIBS+=C:/Program Files/MariaDB 10.1/lib/libmysql.lib" -o Makefile mysql.pro

Then make complains about No such file or directory #include <mysql/mysql.h>:

C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>mingw32-make.exe
mingw32-make.exe -f Makefile.Release all
mingw32-make.exe[1]: Entering directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
g++ -c -pipe -fno-keep-inline-dllexport -O2 -std=c++1y -fno-exceptions -frtti -Wall -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_N
O_CAST_FROM_ASCII -DQT_NO_EXCEPTIONS -DQT_NO_DEBUG -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -IC:/utils/postgresql/pgsql/include
-IC:/utils/my_sql/my_sql/include -IC:/openssl/include -IC:/Program -IFiles/MariaDB -I10.1/include -IC:\Qt\5.6\mingw49_32\include\Q
tSql\5.6.1 -IC:\Qt\5.6\mingw49_32\include\QtSql\5.6.1\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore\5.6.1 -IC:\Qt\5.6\mingw49_32\inc
lude\QtCore\5.6.1\QtCore -IC:\Qt\5.6\mingw49_32\include -IC:\Qt\5.6\mingw49_32\include\QtSql -IC:\Qt\5.6\mingw49_32\include\QtCore
 -I.moc\release -I..\..\..\..\mkspecs\win32-g++  -o .obj\release\main.o main.cpp
In file included from main.cpp:36:0:
../../../sql/drivers/mysql/qsql_mysql_p.h:55:25: fatal error: mysql/mysql.h: No such file or directory
 #include <mysql/mysql.h>
                         ^
compilation terminated.
Makefile.Release:468: recipe for target '.obj/release/main.o' failed
mingw32-make.exe[1]: *** [.obj/release/main.o] Error 1
mingw32-make.exe[1]: Leaving directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
makefile:38: recipe for target 'release-all' failed
mingw32-make.exe: *** [release-all] Error 2

SGaist

If you take a look a the the list of -I options, you'll see that each element between spaces is used. You have to quote the path itself when passing the parameter.

ael16

I tried on another server and got the same errors with "QMYSQL driver not loaded". But after installing the 32 bit version of MariaDB everything was ok. I will not reinstall MariaDB on the first computer atm, but this may be the error here to as I have 32 bit Qt but 64 bit MariaDB. (The new computer used MSVC though)

Thanks for pointing out the error with spaces. I tried to use many kinds of quoting but nothing seemed to work. I used the advice here with dir /x: http://seppemagiels.com/blog/create-mysql-driver-qt5-windows

qmake "INCLUDEPATH+=C:/PROGRA~1/MARIAD~1.1/include" "LIBS+=C:/PROGRA~1/MARIAD~1.1/lib/libmysql.lib" mysql.pro

This was ok. But then there was another error with make. But, as already stated, this may be solved with 32 bit MariaDB. Same error is discussed here: http://www.qtcentre.org/threads/21420-MySQL-driver-Very-strange-problem-PLEASE-HELP-ME-Thanks
But I think this can be marked solved.



C:\Qt\5.6\Src\qtbase\src\plugins\sqldrivers\mysql>mingw32-make.exe
mingw32-make.exe -f Makefile.Release all
mingw32-make.exe[1]: Entering directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
g++ -Wl,-s -shared -Wl,-subsystem,windows -Wl,--out-implib,C:\Qt\5.6\Src\qtbase\plugins\sqldrivers\libqsqlmysql.a -o ..\..\..\..\p
lugins\sqldrivers\qsqlmysql.dll .obj/release/main.o .obj/release/qsql_mysql.o .obj/release/moc_qsql_mysql_p.o  -LC:\utils\postgres
ql\pgsql\lib -LC:\utils\my_sql\my_sql\lib C:\PROGRA~1\MARIAD~1.1\lib\libmysql.lib -LC:\Qt\5.6\mingw49_32\lib C:\Qt\5.6\mingw49_32\
lib\libQt5Sql.a C:\Qt\5.6\mingw49_32\lib\libQt5Core.a .obj\release\qsqlmysql_resource_res.o
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x110): undefined reference to `mysql_num_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x13b): undefined reference to `mysql_stmt_num_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x1da): undefined reference to `mysql_num_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x207): undefined reference to `mysql_stmt_num_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x24e): undefined reference to `mysql_stmt_insert_id@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x28a): undefined reference to `mysql_insert_id@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x478): undefined reference to `mysql_character_set_name@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x6b9): undefined reference to `mysql_errno@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x6d0): undefined reference to `mysql_field_seek@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x6fc): undefined reference to `mysql_field_seek@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x707): undefined reference to `mysql_fetch_field@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x74f): undefined reference to `mysql_fetch_field@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x911): undefined reference to `mysql_error@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x920): undefined reference to `mysql_errno@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xa7a): undefined reference to `mysql_errno@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xae1): undefined reference to `mysql_stmt_error@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xaee): undefined reference to `mysql_stmt_errno@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xc50): undefined reference to `mysql_fetch_row@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xc97): undefined reference to `mysql_stmt_fetch@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xdb0): undefined reference to `mysql_stmt_data_seek@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xdc1): undefined reference to `mysql_stmt_fetch@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xe2e): undefined reference to `mysql_data_seek@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0xe3f): undefined reference to `mysql_fetch_row@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x12e7): undefined reference to `mysql_fetch_lengths@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2418): undefined reference to `mysql_init@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x257e): undefined reference to `mysql_ssl_set@24'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2789): undefined reference to `mysql_real_connect@32'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2894): undefined reference to `mysql_close@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2b9d): undefined reference to `mysql_set_character_set@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2bb4): undefined reference to `mysql_get_client_version@0'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2bd2): undefined reference to `mysql_thread_init@0'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2c4f): undefined reference to `mysql_real_connect@32'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2e5e): undefined reference to `mysql_ssl_set@24'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2ecb): undefined reference to `mysql_options@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2efb): undefined reference to `mysql_options@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x2f2b): undefined reference to `mysql_options@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x3174): undefined reference to `mysql_select_db@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x32b6): undefined reference to `mysql_close@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x32d6): undefined reference to `mysql_options@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x32f4): undefined reference to `mysql_get_server_version@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x36f4): undefined reference to `mysql_thread_end@0'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x36ff): undefined reference to `mysql_close@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x3cd9): undefined reference to `mysql_list_fields@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x3d36): undefined reference to `mysql_fetch_field@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x3d45): undefined reference to `mysql_free_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x3eda): undefined reference to `mysql_query@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x401a): undefined reference to `mysql_query@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x415a): undefined reference to `mysql_query@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x43d6): undefined reference to `mysql_get_server_version@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x47e3): undefined reference to `mysql_list_tables@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4821): undefined reference to `mysql_data_seek@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x482c): undefined reference to `mysql_fetch_row@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4914): undefined reference to `mysql_free_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4bbb): undefined reference to `mysql_num_fields@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4ca5): undefined reference to `mysql_fetch_field@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4d96): undefined reference to `mysql_stmt_result_metadata@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4dc7): undefined reference to `mysql_free_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4de8): undefined reference to `mysql_next_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4e05): undefined reference to `mysql_stmt_close@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4e2b): undefined reference to `mysql_free_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x4ef0): undefined reference to `mysql_store_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x511f): undefined reference to `mysql_real_query@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5220): undefined reference to `mysql_store_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5245): undefined reference to `mysql_field_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5287): undefined reference to `mysql_affected_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x533c): undefined reference to `mysql_fetch_field_direct@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x53bd): undefined reference to `mysql_field_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x557b): undefined reference to `mysql_next_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x55a3): undefined reference to `mysql_store_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x55bd): undefined reference to `mysql_field_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x569b): undefined reference to `mysql_free_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x56e7): undefined reference to `mysql_affected_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x577b): undefined reference to `mysql_fetch_field_direct@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5944): undefined reference to `mysql_stmt_prepare@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x595d): undefined reference to `mysql_stmt_param_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x59dc): undefined reference to `mysql_stmt_init@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5b7a): undefined reference to `mysql_stmt_param_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5c29): undefined reference to `mysql_stmt_reset@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5e1a): undefined reference to `mysql_stmt_param_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5e33): undefined reference to `mysql_stmt_execute@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5f48): undefined reference to `mysql_stmt_affected_rows@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5f78): undefined reference to `mysql_stmt_bind_result@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5f9b): undefined reference to `mysql_stmt_store_result@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x5fc9): undefined reference to `mysql_stmt_bind_result@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x604a): undefined reference to `mysql_stmt_param_count@4'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x6395): undefined reference to `mysql_stmt_bind_param@8'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x67fc): undefined reference to `mysql_stmt_attr_set@12'
.obj/release/qsql_mysql.o:qsql_mysql.cpp:(.text+0x6ae9): undefined reference to `mysql_real_escape_string@16'
C:/Qt/Tools/mingw492_32/bin/../lib/gcc/i686-w64-mingw32/4.9.2/../../../../i686-w64-mingw32/bin/ld.exe: .obj/release/qsql_mysql.o:
bad reloc address 0x4 in section `.data'
collect2.exe: error: ld returned 1 exit status
Makefile.Release:65: recipe for target '..\..\..\..\plugins\sqldrivers\qsqlmysql.dll' failed
mingw32-make.exe[1]: *** [..\..\..\..\plugins\sqldrivers\qsqlmysql.dll] Error 1
mingw32-make.exe[1]: Leaving directory 'C:/Qt/5.6/Src/qtbase/src/plugins/sqldrivers/mysql'
makefile:38: recipe for target 'release-all' failed
mingw32-make.exe: *** [release-all] Error 2

SGaist

You can't mix architectures. While there should be no problem connecting to a 64bit running server with a 32bit client. Loading the 64bit libraries with a 32bit plugin will not work.