Re: Oracle9i: A Beginner's Guide

>
> Question 1:
> -----------------
> What do the letters S Q L stand for when used as an aconym to describe
> Oracle's query interface?

Structured Query Language, often pronounces "sequel", created by IBM during the 1970s.

>
> Question 2:
> -----------------
> What is the difference between SHUTDOWN ABORT and SHUTDOWN IMMEDIATE?
>

SHUTDOWN ABORT halts the Oracle background processes immediately without allowing active transactions to complete. This stops the database altogether and leaves in temporarily in a logically inconsistent state, forcing automatic instance recovery to be required upon startup. This has the same effect on the database as the hardware platform having crashed. In fact, SHUTDOWN ABORT is often used to simulate a hardware or operating system failure during testing.

Instance recovery is automatic and will return the database to a logically consistent state when it is available to the users after it is restarted. The recovery may be time consuming, however, depending on the amount of data that was changed by in-progress, or in-flight transactions at the time of the shutdown. Database transactions that were in in-flight at the time of the shutdown are lost from the SHUTDOWN ABORT and changes made by them are rolled back after the instance is restarted.

SHUTDOWN IMMEDIATE stops the database and processes after completion of active transactions. All in-flight transactions are allowed to complete (from either a COMMIT or a ROLLBACK) and changed data blocks are written to disk such that restarting the database is fast and no instance recovery is necessary. This is one method of achieving a "clean shutdown".

In both cases, the database will be started up with logical consistency between all objects, so no data other than database transactions that were in-flight at the time of the SHUTDOWN ABORT are ever at risk.

> Question 3:
> -----------------
> When in SQL*Plus, wanting to suppress the numbe rof rows returned from
> a SELECT statement, which SET command is used and how is the command
> used?

From the SQL*Plus prompt, SET FEEDBACK OFF or SET FEEDBACK 0 will supress the display of the number of rows returned from a SELECT statement. Other appropriate values are ON or any non-zero integer value.

An integer value will cause that number of rows, at most, to be returned by a SELECT statement, while ON will set the maximum number of returned rows to the default value of 6.

Hope this helps

• ricky

Ricky Sanchez

Don't need a company name, I'm just some dude what knocks about the net. Received on Sun May 20 2001 - 22:11:34 CDT