Oracle Introduction

Features of a relational database:
 

  • A relational database is data-driven, not design-driven.  It is designed once, and the data changes over time without affecting the applications.
  • The data is self-describing.  For example, the phone number type is identified as phone-number_type.
  • Data is stored in one place, read from one place, and modified in one place.  Data is stored once, so maintaining consistency among all applications is easier.
  • Rules that control how the data will be stored are defined and enforced.

    • Oracle 7 is a relational database.  Oracle 8 is a relational-object database, which has some object-oriented implementation.
     

    Oracle Server

    Oracle server runs on dozens of different computers, supporting the following configurations:
     

  • Host-based -- users are connected directly to the same computer on which the database resides.
  • Client/server -- users access the database from their personal computer (client) via a network, and the database sits on a separate computer (server).
  • Distributed processing -- users access a database that resides on more than one computer.  The database is spread across more than one machine, and the users are unaware of the physical location of the data they work with.
  • Web-enabled Computing -- the ability to access data from an Internet-based application

    • Significant features that have catapulted Oracle to the top of the growing information management vendor community:
     

  • Security Mechanisms
  • Backup and Recovery
  • Space Management
  • Open Connectivity
  • Development Tools

    • Components of the Oracle 7/8 Server
     

  • Procedural Component:  stored procedures, database triggers, packages
  • Distributed Processing Component
  • Parallel Query Component
  • Parallel Server Option
  • Video Option -- Oracle Video Option, Oracle Video Client, Oracle Media Net
  • Enterprise Manger
  • Spatial Data Option
  • ConText Option
  • WebServer
  • OLAP Option
  • Advanced Network Option
  • SQL *Plus -- The user-friendly interface
  • Oracle Forms -- The front end
  • Oracle Reports -- The report writer
  • Oracle Book
  • Oracle Loader and SQL *Connect
  • Oracle InterOffice
  • Developer/2000 and Designer/2000

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    Oracle Architecture

    A database is a collection of programs that manipulate datafiles.  Two types of information are stored in an Oracle database:  user data -- your particular application data; and system data -- the data that the database needs to manage itself (e.g. the name and location of all the datafiles associated with a particular database).
     

    A tablespace is a collection of one or more datafiles.  All database objects are stored in tablespaces.  It is called a tablespace because it typically holds a database object called a table.
     

    A table holds Oracle data.  It contains space allocated to hold application-specific data in your database.
     

    A datafile is a file on your disk that stores information.  For example, when working with a word processor, you could call your document a datafile.
     

    An object is a structure defined by the Oracle database and referenced in SQL statements within your application.  Most objects are tables, but SQL statements can refer to other kinds of objects.
     

    An instance is a portion of computer memory and auxiliary processes required to access an Oracle database.
     

    An application is a set of Oracle programs that solve a company's or person's business needs.  In more day-to-day terms, the computer system that generates bills for a hydro-electric utility could be referred to as a billing application.
     

    A DBA or database administrator is a technical wizard who manages the complete operation of the Oracle database.
     
     


     
     

    Oracle Database Objects

    A table  is a database object that holds your data.  Information about every table is stored in the data dictionary; with this information, Oracle allows you to maintain data residing in your table.  A table is made up of many columns, each of those columns has a data type associated with it.

    A view allows you to see a customized selection of one or more tables, and it uses a SQL query that is stored in the database.  When using views, the SQL statement that defines the view is executed as if you had coded the defining statement yourself.  Views can provide an additional level of security.  Views allow you to hide data complexity.  Views help you maintain naming sanity.

    An index is a mini copy of a table.  Index entries for a table allow Oracle rapid access to the data in your tables.
    Indexes have a sorted order; indexes can guarantee uniqueness.
     

    A synonym  is an alternate name for an object in the database.  Think of a synonym as a nickname for an object.
     

    Grants  are privileges given out by owners of objects, allowing other users to work with their data.
     

    A role is a group of privileges that are collected together and granted to users.  Once privileges are granted to a role, a user inherits the role's privileges by becoming a member of that role.  This way, instead of updating every user's account on an individual basis, you can just manage the role.