I just want to store data permanently. Besides the database(I also don’t know how to use database with Unreal), how can I store data permanently so that I can show them in my game ranking module when I start the game.
You can try with this
Searching you can get many references to store data in a database
For an offline game then just a savegame will suffice https://docs.unrealengine.com/latest/INT/Gameplay/SaveGame/Blueprints/
For online games you’ll need a database and an online server to store the database and to handle the read/write requests.
For multiplayer LAN games I’m not sure. An online database would be the most straightforward way to do it, but perhaps it can be done with savegames.
SaveGame files work fine for LAN games.
SaveGame if you want it to save between games, for between levels use a Game Instance.