The DBMS I'm using now is O10, the oracle client is 11g, and the database server is 12c. Officially, if the client is 11g or 12c, the DBMSs need to use ORA, so I have a few questions.
1. Why did I use O10 to connect to the database without an error?
2.The DBMS used by the system I am now involved in is O73 database server is oracle 9i. I used O10 after system migration. Will an error occur if I continue to use it?