I had complied qsqlmysql.dll.

[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:

[jsulm]

@yuyu I'm confused: before you posted output showing that the plug-in was loaded.
Now you posted output showing that it could not be loaded.

Please do again what was suggested before: set QT_DEBUG_PLUGINS and if the plug-in fails to load post the output here...

[yuyu]

@jsulm you can try it ,it may be a problem,you can use mysql 8.0.28 and qt6.3 , you can find this error.

[jsulm]

@yuyu I'm not going to try anything.
I suggested what you can do to get help.
It is up to you to do that or not...

[yuyu]

@jsulm I think it's a waste of time, regardless of the problem

[Nevez]

@yuyu
I am using Mysql 8.x.x and QT 6.2.3. Mysql works fine too.
According to the error you get, you may have placed the relevant DLL in the wrong place or you may have used the wrong version DLL.
There was a video on youtube that did this well. You will find it on your first search.

[yuyu]

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

I am using Mysql 8.x.x and QT 6.2.3. Mysql works fine too.
According to the error you get, you may have placed the relevant DLL in the wrong place or you may have used the wrong version DLL.
There was a video on youtube that did this well. You will find it on your first search.

I user mysql >8.0.19,I see the doc, tha say

[Nevez]

@yuyu
so i am using 8.0.27, i recommend you too.

[yuyu]

@Nevez en,than you very much .I think it is ok ,I will use 8.0.27.That is a good idea.