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Lesson 2 Oracle database structure
Objective Identify the primary components of an Oracle database.

Oracle Database Structure

When you look at an Oracle database system, you may be surprised by what you do not find included. Oracle's basic database system has no design tools, no form-building tools, and no report-building tool. What you do get, however, is arguably the best database engine in the industry.
For sheer computing power, Oracle is the Cadillac of database systems and can support thousands of concurrent users, terabytes of data, and millions of transactions per second.

Components

Oracle’s components are divided into two groups:
  1. Server components: Server components run in the central computer that stores your data and handles transactions from other components.
  2. Client components: These can be run in the same computer as the server components or (more typically) can be run on remote computers that are connected to the server computer via a network.

Use your mouse to view information about the components that make up the Oracle database.

  1. Oracle can be installed on Windows, UNIX, IBM, Solaris, SGI, and many other platforms. It can also be installed on parallel servers.
  2. The Oracle object-relational database server handles all your data, security, and file management processes. Each Oracle database is called a database instance.
  3. Relational tables are stored in the database, including their structure, data, relationships to other tables, and privileges granted to users for viewing and modifying the table. Tables are grouped into sets called schemas.
  4. The underlying file structure is defined by the Database Administrator (DBA). In general, a table is mapped to a logical tablespace, which is in turn mapped to one or more physical files.
  5. Object tables are stored the same way as relational tables.
  6. Oracle Network Services is the communication conduit between the database server and Oracle tools on both the server and the client side.
  7. SQL*Plus is the programming environment where you can create and execute SQL code.
  8. Use EXP (a command line call) to export database information into a compressed and portable file. Use IMP to read the compressed file and import the information into another Oracle database instance.
  9. Use Loader to read files in a variety of formats (such as the typical comma-delimited file) and load the information into Oracle tables.
  10. Oracle provides pre-compilers for various languages, such as COBOL and FORTRAN. These simplify programming by allowing you to embed SQL code directly into your application code.
  11. The Server Manager (svrmgr) program is a command line environment for use by the DBA to start and stop the database and to run SQL commands.
  12. Oracle supports client software on many platforms, including Windows NT, Windows 95, and UNIX.
  13. SQL*Plus appears on both the client and server side. On the client side, SQL*Plus has a Windows-like look and feel
  14. Several database assistants are packaged with the client software, including one for creating Web-based reports and one for converting Microsoft Access tables into Oracle tables.
  15. Enterprise Manager is a complete set of Java-based tools for managing your Oracle database, from creating users and tables to signaling you by email when your database runs out of space.
  16. Net8 appears on the client side as a communication link between the client and the server. Transactions are translated to standard network protocols (such as TCP/IP).
Oracle Database Components

In addition to these core components, there are dozens of add-on components for sale from Oracle. For example, the Oracle Developer package includes a graphical user interface (GUI) for designing reports, graphs, and data entry forms.
You can also use Open Database Communication (ODBC) or Java Database Communication (JDBC) to connect the Oracle database to third-party software, such as Microsoft Access.
  1. (ODBC) Open Database Connectivity: A set of standards that define communication protocol and syntax to be used when interacting with any relational database.
  2. (JDBC) Java Database Connectivity: A set of standards defining a standard protocol and syntax in Java applications or applets to interact with any relational database.
The next lesson shows you how to see what users, tables, object tables, and other objects are stored in your Oracle database.