AG Algorithmic Adventurer

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Qt 5.13 MySql connection on macOS Mojave and MAMP

Today I went crazy because I tried to connect to a mysql server, running inside a MAMP session, using Qt 5.13 on macOS Mojave.

This is what I did. First I created a demo project with Qt Creator. A console program. Very basic.

// Filename main.cpp
#include <QCoreApplication>
#include <QtSql>
#include <QDebug>

int main(int argc, char *argv[])
  QCoreApplication a(argc, argv);
  auto db = QSqlDatabase::addDatabase("QMYSQL");

  if ( ! ) {
    qDebug() << db.lastError();
    qFatal("Could not load database!");

  qDebug() << "Connected.";

  QSqlQuery q(db);
  q.prepare("SELECT * FROM DividendData");
  if ( ! q.exec() ) {
      qDebug() << q.lastError();
  } else {
      qDebug() << "Read data.";
      QSqlRecord record = q.record();
      int cols = record.count();

      QString temp;
      for ( int c = 0; c < cols; c++ ) {
          temp += record.fieldName( c ) + (( c < cols - 1 ) ? "\t" : "" );
      qDebug() << temp;

      while ( ) {
          temp = "";
          for ( int c = 0; c < cols; c++ ) {
              temp += q.value( c ).toString() + ( ( c < cols - 1 ) ? "\t" : "" );
          qDebug() << temp;


  return a.exec();

And the .pro file:

QT -= gui
QT += sql

CONFIG += c++11 console
CONFIG -= app_bundle


# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

After compiling and running the program I’ve got an error message

$ ./qtsqltest 
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC QODBC3 QPSQL QPSQL7
QSqlError("", "Driver not loaded", "Driver not loaded")
Could not load database!
Abort trap: 6

Ok. So the QMYSQL driver is not available.

Now. After several hours of research, test and frustration I found the solution. You have to build the mysql plugin for Qt yourself. This is how:

Install mysql-client

First, if not already done install the mysql-client with homebrew.

$ brew install mysql-client
$ ll /usr/local/Cellar/mysql-client/
total 0
drwxr-xr-x   3 arnegockeln  staff    96B 11 Jul 12:20 .
drwxrwxr-x  11 arnegockeln  admin   352B 11 Jul 14:57 ..
drwxr-xr-x  10 arnegockeln  staff   320B 11 Jul 12:20 5.7.23

Build libqsqlmysql.dylib

Second, within your Qt Creator you open the sqldriver project for mysql. My Qt installation is in ~/sourcecode/sdk/QtLatest/5.13.0. From there the mysql sqldriver project is in the folder: ~/sourcecode/sdk/QtLatest/5.13.0/Src/qtbase/src/plugins/sqldrivers/mysql/

Now add two lines to the file:

TARGET = qsqlmysql

HEADERS += $$PWD/qsql_mysql_p.h
SOURCES += $$PWD/qsql_mysql.cpp $$PWD/main.cpp

QMAKE_USE += mysql

OTHER_FILES += mysql.json


# add this two lines with your path to the mysql-client
INCLUDEPATH += "/usr/local/Cellar/mysql-client/5.7.23/include"
QMAKE_LIBDIR += "/usr/local/Cellar/mysql-client/5.7.23/lib"

Build the project.

If you wonder why there is no file in build-mysql-Debug, Qt Creator moves the compiled driver dylib to the folder ~/sourcecode/sdk/QtLatest/5.13.0/Src/qtbase/plugins/sqldrivers/. But that is not what we want.

Move dylib to correct directory

We need to copy the dylib to the correct location. That is ~/sourcecode/sdk/QtLatest/5.13.0/clang_64/plugins/sqldrivers/.

$ pwd
$ cp Src/qtbase/plugins/sqldrivers/libqsqlmysql* clang_64/plugins/sqldrivers/


Now the QMYSQL driver is available to Qt and you can compile and run your program again.