This plugin requires NBT API
https://www.spigotmc.org/resources/nbt-api.7939/
config.yml is here----
mysql:
host: 192.168.0.1
port: 3306
database: minecraft
username: minecraft
password: password
The structure of database is here----
DatabaseName: $database
TablesName: player, inventory, enderchest
playerTable has player_id(auto_increment) and player_name
Before install this plugin, you need to check if the player_table is clear.
If there player_id, the player's inventory will be written when he login.