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https://docs.oracle.com/database/121/ADMQS/GUID-DE8A79BD-FAE4-4364-98FF-D2BD992A06E7.htm
https://docs.oracle.com/database/121/NTDBI/startrdb.htm
https://docs.oracle.com/database/121/ADMQS/GUID-E2807CDE-1401-4A79-8131-EBC6D45C71B4.htm
https://www.dummies.com/programming/databases/how-to-connect-to-the-oracle-12c-database-instance/
http://www.oracletutorial.com/getting-started/connect-to-oracle-database/
https://dba.stackexchange.com/questions/101479/oracle-12c-database-cannot-log-in-as-a-local-user
https://dba.stackexchange.com/questions/140032/how-to-connect-to-oracle-12c-from-sqlplus-without-password-in-command-line
https://www.dell.com/support/article/us/en/04/sln310924/how-to-connect-to-pluggable-databases-in-oracle-rac-12cr1-
https://stackoverflow.com/questions/41083540/i-cant-login-to-oracle-system-account
https://stackoverflow.com/questions/49030388/how-to-connect-to-oracle-12c-database-using-cx-oracle
https://de.wikipedia.org/wiki/Oracle_(Datenbanksystem)
https://oracle-base.com/articles/12c/sqlplus-enhancements-12c
https://www.quora.com/How-can-I-connect-PHP-with-Oracle-12c-database