Relationship between catalog, schema, user, and database instance

Question

To compare databases of different vendors (Oracle, SQL Server, DB2, MySQL, and PostgreSQL) how can I identify any object uniquely and do I need a catalog? For instance, In J

Answer 1

What is mentioned here about mysql in post by filiprem seems to be incorrect. As per following links, in mysql the jdbc catalog corresponds to database. The jdbc schema is not supported .

• http://forums.mysql.com/read.php?39,137564,137629#msg-137629
• http://bugs.mysql.com/bug.php?id=23304
• http://books.google.com/books?id=a8W8fKQYiogC&pg=PA25&lpg=PA25&dq=jdbc+catalog+schema&source=bl&ots=oj0HAA91zL&sig=vRjgPLV_3J6o2kqh6epwvZNZgcM&hl=en&sa=X&ei=3k7zT-_qBueW2AXSjdDkAw&ved=0CFYQ6AEwAg#v=onepage&q=jdbc%20catalog%20schema&f=false