I had complied qsqlmysql.dll.

[yuyu]

I use mysql 8.0

mysqld --initialize --console
mysqld install
net start mysql

I complied my driver,like this

I had complied qsqlmysql.dll qsqlmysql.debug.

And I copy it to C:\Qt\6.3.0\mingw_64\plugins\sqldrivers.
I copy to libmysql.dll and libmysql.lib to C:\Qt\6.3.0\mingw_64\bin.

when I run my application,has some error .

1.QSqlDatabase: QMYSQL driver not loaded
2.command aborted

       database=QSqlDatabase::addDatabase("QMYSQL","asd");
    database.setHostName("127.0.0.1");
    database.setDatabaseName("mydb");     
    database.setUserName("root");
    database.setPassword("123456");   
    if (!database.open()) {

        qDebug()<<database.lastError();
    }

help me , I am crazying.

[Christian Ehrlicher]

@yuyu said in I had complied qsqlmysql.dll.:

help me , I am crazying.

Why not using the search function? It's a very powerful thing...

[yuyu]

I do not find the answer, I used qt6.3.

[yuyu]

QLibraryPrivate::loadPlugin failed on "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\Qt\6.3.0\mingw_64\plugins\sqldrivers\qsqlmysql.dll

but there has the qsqlmysql.dll,i complied

[Christian Ehrlicher]

You should post the whole output of QT_DEBUG_PLUGINS and make sure (as in all other threads you will find here) that the dependencies of the plugin (= mysql dlls) are found - so that they're either in the path or parallel to the plugin.

[yuyu]

I had success when I use mysql5.7,but the same way it is error when I use mysql8

[jsulm]

@yuyu As @Christian-Ehrlicher suggested set QT_DEBUG_PLUGINS environment variable to 1 before running your app and then check its out put - it should tell you why qsqlmysql.dll could not be loaded.

[yuyu]

@jsulm I Had set but it tell me load error.I look up the qt doc.

I do not know what is mean the note.

[yuyu]

@jsulm said in I had complied qsqlmysql.dll.:

QT_DEBUG_PLUGINS

[jsulm]

@yuyu Please post text not images.
We need to see the actual error after :
Currently there are unreadable characters.

[yuyu]

@jsulm

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QSQLITE")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QMYSQL",
            "QMARIADB"
        ]
    },
    "archlevel": 2,
    "className": "QMYSQLDriverPlugin",
    "debug": true,
    "version": 393984
}

qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\\Qt\\6.3.0\\mingw_64\\plugins\\sqldrivers\\qsqlmysql.dll

I had success when i use mysql5.7 ,but the same way there has error when i use mysql8.0.22

[jsulm]

@yuyu said in I had complied qsqlmysql.dll.:

qsqlmysql.dll

In your other output there is some unreadable characters after qsqlmysql.dll:
Can you provide that part as readable text?

[yuyu]

@jsulm the unreadable characters is what I use qDebug output chineses，I had delete it.
now
mycode

 qDebug() << QSqlDatabase::drivers();

    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setPort(3306);
    db.setDatabaseName("mydb");
    db.setUserName("root");
    db.setPassword("123456");
    bool ok = db.open();

the console

16:45:13: Debugging D:\1a_perfect\build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug\debug\testsql.exe ...
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/platforms" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/platforms/qdirect2d.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/platforms/qdirect2d.dll, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "direct2d"
        ]
    },
    "archlevel": 2,
    "className": "QWindowsDirect2DIntegrationPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("direct2d")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/platforms/qminimal.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/platforms/qminimal.dll, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "archlevel": 2,
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimal")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/platforms/qoffscreen.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/platforms/qoffscreen.dll, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "archlevel": 2,
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("offscreen")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/platforms/qwindows.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/platforms/qwindows.dll, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "windows"
        ]
    },
    "archlevel": 2,
    "className": "QWindowsIntegrationPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("windows")
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/platforms" ...
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/platforms/qwindows.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/platformthemes" ...
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/platformthemes" ...
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/styles" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/styles/qwindowsvistastyle.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/styles/qwindowsvistastyle.dll, metadata=
{
    "IID": "org.qt-project.Qt.QStyleFactoryInterface",
    "MetaData": {
        "Keys": [
            "windowsvista"
        ]
    },
    "archlevel": 2,
    "className": "QWindowsVistaStylePlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("windowsvista")
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/styles" ...
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/styles/qwindowsvistastyle.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/iconengines" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/iconengines/qsvgicon.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/iconengines/qsvgicon.dll, metadata=
{
    "IID": "org.qt-project.Qt.QIconEngineFactoryInterface",
    "MetaData": {
        "Keys": [
            "svg",
            "svgz",
            "svg.gz"
        ]
    },
    "archlevel": 2,
    "className": "QSvgIconPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("svg", "svgz", "svg.gz")
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/iconengines" ...
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/imageformats" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qgif.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/imageformats/qgif.dll, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "gif"
        ],
        "MimeTypes": [
            "image/gif"
        ]
    },
    "archlevel": 2,
    "className": "QGifPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("gif")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qico.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/imageformats/qico.dll, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "ico",
            "cur"
        ],
        "MimeTypes": [
            "image/vnd.microsoft.icon",
            "image/vnd.microsoft.icon"
        ]
    },
    "archlevel": 2,
    "className": "QICOPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("ico", "cur")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qjpeg.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/imageformats/qjpeg.dll, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "jpg",
            "jpeg"
        ],
        "MimeTypes": [
            "image/jpeg",
            "image/jpeg"
        ]
    },
    "archlevel": 2,
    "className": "QJpegPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("jpg", "jpeg")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qsvg.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/imageformats/qsvg.dll, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "svg",
            "svgz"
        ],
        "MimeTypes": [
            "image/svg+xml",
            "image/svg+xml-compressed"
        ]
    },
    "archlevel": 2,
    "className": "QSvgPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("svg", "svgz")
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/imageformats" ...
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qgif.dll" loaded library
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qico.dll" loaded library
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qjpeg.dll" loaded library
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/imageformats/qsvg.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlite.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlite.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QSQLITE"
        ]
    },
    "archlevel": 2,
    "className": "QSQLiteDriverPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QSQLITE")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QMYSQL",
            "QMARIADB"
        ]
    },
    "archlevel": 2,
    "className": "QMYSQLDriverPlugin",
    "debug": true,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QMYSQL", "QMARIADB")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlodbc.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlodbc.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QODBC"
        ]
    },
    "archlevel": 2,
    "className": "QODBCDriverPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QODBC")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlpsql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlpsql.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QPSQL"
        ]
    },
    "archlevel": 2,
    "className": "QPSQLDriverPlugin",
    "debug": false,
    "version": 393984
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QPSQL")
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/sqldrivers" ...
QList("QSQLITE", "QMARIADB", "QMYSQL", "QODBC", "QPSQL")
qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/accessible" ...
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/accessible" ...
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.3.0/mingw_64/plugins/accessiblebridge" ...
qt.core.plugin.factoryloader: checking directory path "D:/1a_perfect/build-testsql-Desktop_Qt_6_3_0_MinGW_64_bit-Debug/debug/accessiblebridge" ...

[jsulm]

@yuyu said in I had complied qsqlmysql.dll.:

qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" loaded library

Looks good now

[yuyu]

@jsulm I can not connect my mysql database .

[jsulm]

@yuyu What does db.open() return?
What does https://doc.qt.io/qt-5/qsqldatabase.html#lastError return after open() call?

[Nevez]

@yuyu Still getting driver not installed error? and yes share the result of db.open() as well.

[yuyu]

@jsulm false

[jsulm]

@yuyu I asked two questions. Would you be so kind to also answer the second one?

[yuyu]

@Nevez yes，but I had install it. it return false.
sometime has

qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\\Qt\\6.3.0\\mingw_64\\plugins\\sqldrivers\\qsqlmysql.dll: