http://www.rastertek.com/oratut04.html
user vs schema ; schema creation.
https://docs.oracle.com/cd/B19306_01/appdev.102/b14261/subprograms.htm
(Sub programs of PLSQL / especially function/procedure overloading)
Tag: oracle
Oracle Joins
https://docs.oracle.com/cd/B28359_01/server.111/b28286/queries006.htm#SQLRF52339
official documentation.
https://stackoverflow.com/questions/6559261/left-outer-join-using-sign-in-oracle-11g
Tip: In Oracle, (+) denotes the “optional” table in the JOIN.