Oracle 4

WHY ORACLE ? Oracle is an open system i.e. the database is accessing by different data access languages like SQL, Visual Basic, Power Builders,Delphi,VC++,JAVA etc. Oracle supports database upto gigabytes in size. * Oracle supports large number of concurrent users. * Oracle supports true client/server environment.if enable processing to be spilt between database server and the client application programs. * Oracle provides high levelof data security in terms of users, passwords privileges, and permissions. * Oracle database behaves same on all platform line Windows,Unix,Dos,Mainframes etc.
Structure of Oracle Database:
physical structure: one or more data files, Two of more log files, One control file. Logical structure: Table spaces, Segments, Extents, Data blocks.
The data files contain all user data in terms of tables, index, and views. The log files contain the information to open and be recovered, of Undone after a transaction(Rollback).
The control file physical data, media information to open and manage data files .If the control file is damaged the server will not be able to open are use the database even if
the database is undamaged.
What are the Back ground processes in Oracle and what are they. ? There are basically 9 Processes but in a general system we need to mention the first five background processes. They do the house keeping activities for the Oracle and are common
in any system. a) Data Base Writer(DBWR) :: Data Base Writer Writes Modified blocks from Database buffer cache to Data Files.This is required since the data is not written whenever a transaction is commited. b)LogWriter(LGWR) :: LogWriter writes the redo log entries to disk. Redo Log data is generated in redo log
buffer of SGA. As transaction commits and log buffer fills, LGWR writes log entries into a online
redo log file. c) System Monitor(SMON) :: The System Monitor performs instance recovery at instance startup. This is useful for recovery from system failure. d)Process Monitor(PMON) :: The Process Monitor peforms process recovery when user Process fails. Pmon Clears and Frees resources that process was using. e) CheckPoint(CKPT) :: At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate
the most recent checkpoint. f)Archieves(ARCH) :: The Archiver copies online redo log files to archival storal when they are busy. g) Recoveror(RECO) :: The Recoveror is used to resolve the distributed transaction in network h) Dispatcher (Dnnn) :: The Dispatcher is useful in Multi Threaded Architecture i) Lckn :: We can have upto 10 lock processes for inter instance locking in parallel sql.

Oracle 3

The Oracle Environment Oracle is a modular system that consists of the Oracle database and several functional programs. Oracle's tools do four major things of work. 1. Database Management. 2. Data access and Manipulation. 3. Programming 4. Connectivity.
Database Management Tools
This (is usually known as RDBMS by oracle) includes the core programs for Oracle's database management system, the Oracle database with its associated tables and views, which are stores information related to every fact of the database system.User name, user access rights, table attribute, storage information and auditing data for disaster recovery are stored in the data dictionary.
The Database Administrator
The person responsible for a Database is called the DatabaseAdministrator(DBA).The DBA has a special set of previleges and has complete over the database.Any system with more than one user should have a DBA.The function of DBA include. Creating primary database storage structures. Modifying the structure of the database. Backing up and restoring the database.
Monitoring database performance and efficiency. Transfering data between database and external files. Manipulating the phisical location of the database.
THE END USER End user have less complex but equally important tasks.They must be able to · Query the database. · Generate printed output. · Share data with or secure data from others. · Use non-export methods to update the database. · Define applications from a user point of view.

Oracle 2

Oracle the Right Tool To keep track of records is often the best reason to consider buying a software package.Choosing a proven product increase the chance that we will get a system capable of meeting all our needs .Oracle has had many years in the relational market to often on the large,Complex applications. Although Oracle demands greater expertise on the part of the application developed,an application developed oracle will be able to keep pace with growth and change in the world at large.
Oracle Gives You Security and Control
Oracle has several features that ensure the integrity of the data base. If an interruption occurs in processing, a Rollback can reset the database to a point before the disaster. If a restore is necessary, Oracle has a Roll forward command for recreating your database to its mast resent save point.
Oracle provides user with several functions for securing data. Grant and Revoke commands limit access to information down to the row and column levels. Views are valuable feature for limiting access to the primary tables in the database.

Introduction to Oracle

Introduction to Oracle. Oracle is a comprehensive operating environment that packs the power of mainframe relation database management system into user's micro computer. It provides a set of functional programs that user can use as tools to build structures and perform tasks. Because applications are developed on oracle are completely portable to the other versions of the programmer can create a complex application in a single user, environment and them move it to a multi user platform.Users do not have to be an expert to appriciate Oracle but the better user understand the program,the more productively and creatively he can use the tools it provides Relational Database Management system A Relational Database Management System (RDBMS) can perform a wide range of tasks. It acts as a transparent interface between the physical storage and the logical presentation of data.It provides a set of more or less flexible and sofesticated tools for handling information. Users can use the tools to
· Define a Database
· Query the Database
· Add,Edit and Delete data.
· Modify the structure of the Database.
· Communicate with in the Networks.
· Exports and Imports the data.
· Security.