ORA-00019 Maximum number of session licenses exceeded
Cause: All licenses are in use. Action: Increase the value of the LICENSE MAX SESSIONS initialization parameter.
ORA-00018 Maximum number of sessions exceeded
Cause: All session state objects are in use. Action: Increase the value of the SESSIONS initialization parameter.
ORA-00017 Session requested to set trace event
Cause: The current session was requested to set a trace event by another session. Action: This is used internally; no action is required.
ORA-00001 unique constraint (%s.%s) violated
Cause: An UPDATE or INSERT statement attempted to insert a duplicate key. For Trusted Oracle configured in DBMS MAC mode, you may see this message if a duplicate entry exists at a different level. Action: Either remove the unique restriction or do not insert the key.
ORA-12502 TNS-12502 TNS:listener received no CONNECT_DATA from client
TNS:listener received no CONNECT_DATA from clientCause: No CONNECT_DATA was passed to the listener.Action: Check that the service name resolved from TNSNAMES.ORA has the CONNECT_DATA component of the connect descriptor. Below is the sample entry of tnsnames.ora:- #When using SERVICE_NAME in CONNECT_DATA componentorcl.example.com = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = myserver.example.com)(PORT =…
Oracle Database Internal Mechanism 