Qsqldatabase: solution of qmmysql driver not loaded

Yesterday I helped people set up an attendance management project , No more details , Anyway, I set up the project , Get ready sql Environmental Science , Tips ：QSqlDatabase: QMYSQL driver not loaded, then debug Up to now …
No matter how , I give my solution , I hope this article can help you .

Qt Connect MySql You need to connect to Qt Database plug-in for , Then connect to MySql Dynamic library , To be able to use MySql.
The dynamic library plug-in is mysql Self contained , We need to compile the database plug-in by ourselves .
Although a little cumbersome , But it's not difficult .

Install and configure environment variables

here Be sure to check Source Source folder For later compilation .
No matter the runtime of your project （kit） What is it? , The next steps are the same . Only the database plug-in and dynamic library plug-in are placed in different positions , Which library does your project use , Just put the database plug-in and dynamic library plug-in QT Which library .
I won't say more about environment variable configuration , There must be this bug All have been configured .

compile mysql drive

Open folder D:\QT\5.14.2\Src\qtbase\src\plugins\sqldrivers\mysql
Of course, we may have different installation positions , without Src First step .
stay Qt Open in mysql.pro
Comment out QMAKE_USE += mysql, Add three lines of code ：

win32:LIBS += -LD:\mysql\lib\ -llibmysql
INCLUDEPATH += D:/MySql/include
DEPENDPATH += D:/MySql/include

The first line is to use \mysql\lib\ Under the libmysql Folder , The second and third lines are using /MySql/include Folder
The effect is as follows ：

Watch out! , There must be no spaces in the path
If mysql There are spaces in the path , It needs to be reloaded .
So it's really troublesome
after structure file , At the root D:\plugins\sqldrivers Find three or four files under ：

Generated qsqlmysql.dll qsqlmysqld.dll Copy to Qt Corresponding mingw Of sqldrivers in .
Here are three , Tests can also .

Copy sql Dynamic library

Copy mysql Dynamic library , take mysql/lib Medium libmysql.dll （ Dynamic library ） Copy to Qt Corresponding compiler bin Under the table of contents

Test connection

New projects , Or there are already non conflicting projects
stay .pro Add... To the document QT += sql
Use the following code to print the available database version

#include "mainwindow.h"
#include <QDebug>
#include <QApplication>
#include <QtSql/QtSql>
int main(int argc, char *argv[])
{
    
    QApplication a(argc, argv);
    QStringList drivers = QSqlDatabase::drivers();  // Get the currently available database drivers 
    foreach(QString driver, drivers)
    qDebug() << driver;

    MainWindow w;
    w.show();
    return a.exec();
}

appear ：QMYSQL

Success .

Please leave a message if you have any questions , I will reply in six hours , Probably .