Je voudrais exporter le nom du fichier, la légende et les mots-clés dans une autre base de données phpmyadmin ! Cela est-il possible ?
You can export the metadata to an XMP sidecar file for proprietary raw images. Note that the data (change) is also kept in the Lightroom database. For more info refer Metadata basics and actions in Lightroom
To automatically write changes into files (or into XMP sidecar files) choose Catalog Settings > Metadata > Automatically Write Changes into XMP. Linked a tutorial.
Directly, it is not possible. However, indirectly....
The Lightroom catalog is a SQLite database. I have seen references to an ODBC driver for SQLite. This would allow you to import the data into a spreadsheet or other database. The catch is that the catalog is not publicly documented. If you are not familiar with relational databases, navigating through the catalog may be difficult.
If you search for plug-ins, you should find some that will export metadata for you.