This is Microsoft SQL Server.

I misread the OP's original MSSQL-Server as MySQL-Server!

This is Microsoft SQL Server. There does not seem to be an ODBC equivalent option on the Qt side. There may be an ODBC connection string option that achieves the same thing but I could not see one in a brief look.

@Andy314 Never done this myself, so take this with a good deal of skepticism.

Your application should receive a Windows WM_POWERBROADCAST message when it wakes. This message can be intercepted using a filter installed with QCoreApplication::installNativeEventFilter(). From there you could trigger a reconnection. You could possibly use this to make your database connection quiesce gracefully on suspend.

It works !
Here is the code from Chat-GPT:

#include <QCoreApplication>
#include <QAbstractNativeEventFilter>
#include <QDebug>
#include <windows.h>

class PowerEventFilter : public QAbstractNativeEventFilter
{
public:
    virtual bool nativeEventFilter(const QByteArray &eventType, void *message, long *result) override
    {
        Q_UNUSED(eventType);
        Q_UNUSED(result);

        MSG* msg = static_cast<MSG*>(message);
        if (msg->message == WM_POWERBROADCAST) {
            switch (msg->wParam) {
                case PBT_APMPOWERSTATUSCHANGE:
                    qDebug() << "Power status changed.";
                    break;
                case PBT_APMSUSPEND:
                    qDebug() << "System is suspending operation.";
                    break;
                case PBT_APMRESUMEAUTOMATIC:
                    qDebug() << "Operation resuming automatically after event.";
                    break;
                // ... handle other cases ...
            }
        }
        return false;
    }
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    PowerEventFilter filter;
    a.installNativeEventFilter(&filter);

    return a.exec();
}

Your application should receive a Windows WM_POWERBROADCAST message when it wakes. This message can be intercepted using a filter installed with QCoreApplication::installNativeEventFilter(). From there you could trigger a reconnection. You could possibly use this to make your database connection quiesce gracefully on suspend.