Oracle

You can create a backup of a table (structure and data) in Oracle by using the following syntax: CREATE TABLE customers_backup AS (SELECT * FROM customers) The previous example creates the customers_backup table which mirrors the structure and data of the customers table.

Sometimes you might need to commit a single INSERT, UPDATE or DELETE statement and not the whole main transaction. In such a case you can use an AUTONOMOUS TRANSACTION which is a feature available since Oracle 8i. The trick is to encapsulate the statement in a procedure and use the pragma AUTONOMOUS_TRANSACTION. Here is an example, suppose you have a table, your_table, which has just one column of type NUMBER and you want to insert the value 1, irrespective of the state of the main transaction:

In Oracle you can execute hierarchical queries using some cool operators–CONNECT BY PRIOR, START WITH and the pseudocolumn SYS_CONNECT_BY_PATH, namely. However, using your fantasy you can exploit these operators to put in a single row–with each item separated by the next through a separator, such as a comma–what you have in multiple rows. For example if you have more than one telephone number in different rows and you want to put them in a single comma-separated row you could use a query similar to the following: