Run a Query to Show All Table

Mysql:
This allows you to see all existing tables inside the database selected.
mysql> SHOW TABLES;

Oracle:
Oracle doesn't support the above command, though an equivalent would be to use this sql statement:
sql > SELECT * FROM tab WHERE TABLE_TYPE = 'TABLE';
or
sql > SELECT * FROM cat WHERE TABLE_TYPE = 'TABLE';
or
sql > select * from user_objects where object_type = 'TABLE';

SQL Server:
Run the script below in your query analyzer.
SELECT * FROM INFORMATION_SCHEMA.TABLES where TABLE_TYPE = 'BASE TABLE'