This question already has an answer here:
With the database manager in QGIS, it is possible to export a QGIS layer to a PostgreSQL database, by creating a new table in the database. For instance, if I have a
cities layer in my QGIS project, I can export it to a new table
cities in my PostgreSQL database.
The tool provides the option of replacing the destination table in the database, if this table already exists (see screenshot below, sorry about the French locale).
Now, my question is: is there any way to "concatenate" the data of my QGIS layer
cities to the existing
citiestable of my PostgreSQL database, instead of erasing the existing table and replacing it by a new one?
(assuming of course, that the existing database table and the QGIS layers have the same CRS and the same geometry type)