About Oracle - sql plus , how can i get a list of the existing databases ?? what commands should i use?

Question

i remember in mySQL was something like:
show databases;
and then "use"+" database"; to position to that DB
and then "show tables" to see the tables on that DB

Answer 1

There are several system tables you can look at. It depends on which tables you want to see and your authority level.

DBA_tables holds all the tables in the database but can only be accessed by those with DBA authority.
user_tables holds all the tables owned by the current user
all_tables holds all the tables that the current user can see

Use 'select table_name from all_tables' to see the list of tables you can access. Replace table_name with * to get all the information held there.

There is a lot of metadata held in the Oracle data dictionary. For a start look at http://en.wikipedia.org/wiki/Oracle_metadata. One of my favorites http://www.oreilly.com/catalog/oracleddpr/chapter/ch01.pdf

Answer 2

SQL is an abreviation for Structured Query Language and Oracle SQL Plus is a tool for SQL, It simply means that SQL Plus gives you a platform for Executing SQL Statements