Thanks. First you can take a look about the ledger info (world state and blockchain of transaction logs) here. You can find what and where about database.
Meanwhile, I am interested to know your purpose of “change data manually”. For a successful deployment, you should avoid manual operation on the database (no matter the blockchain or the world state) as it is against the purpose of using blockchain (immutability and traceability). In general the blockchain (transaction logs) and world state should be updated through chaincode only, which is the logic agreed by all parties before deployment.
Hope this helps.