Introducing Oracle for beginners

What is Oracle?
Its a RDBMS.Relational Database Management System.
Oracle - It is a Greek word meaning God- Who fulfils all the Dreams.
Oracle Inc is the world's largest supplier of relational databaseproducts (notably Oracle9i), which are used most of the Fortune 500companies and of course by all the leading E-business and Internetsites.
Oracle's relational database was the world's first to support theStructured Query Language (SQL), now an industry standard.Founder of Oracle Inc: CEO Lawrence J. Ellison and a few associatesformed Oracle in 1977.
What is a RDBMS?
A relational database is a collection of data items organized as a setof formally-described tables from which data can be accessed orreassembled in many different ways without having to reorganize thedatabase tables. The relational database was invented by E. F. Codd at IBM in 1970.The standard user and application program interface to a relationaldatabase is the structured query language (SQL). SQL statements are usedboth for interactive queries for information from a relational databaseand for gathering data for reports.
What Are Codd's Rules?
Dr. E. F. Codd's 12 rules for defining a fully relational database.
Note that based on these rules there is no fully relational databasemanagement system available today. In particular, rules 6, 9, 10, 11 and12 are difficult to satisfy.

• Foundation Rule:A relational database management system must manage its stored datausing only its relational capabilities.
• Information Rule All information in the database should be represented in one and onlyone way - as values in a table.
• Guaranteed Access Rule Each and every datum (atomic value) is guaranteed to be logicallyaccessible by resorting to a combination of table name, primary keyvalue and column name.
• Systematic Treatment of Null Values Null values (distinct from empty character string or a string of blankcharacters and distinct from zero or any other number) are supported inthe fully relational DBMS for representing missing information in asystematic way, independent of data type.
• Dynamic On-line Catalog Based on the Relational Model The database description is represented at the logical level in the sameway as ordinary data, so authorized users can apply the same relationallanguage to its interrogation as they apply to regular data.
• Comprehensive Data Sublanguage Rule A relational system may support several languages and various modes ofterminal use. However, there must be at least one language whosestatements are expressible, per some well-defined syntax, as characterstrings and whose ability to support all of the following iscomprehensible:data definitionview definitiondata manipulation (interactive and by program)integrity constraintsauthorizationtransaction boundaries (begin, commit, and rollback).
• View Updating Rule All views that are theoretically updateable are also updateable by the system.
• High-level Insert, Update, and Delete The capability of handling a base relation or a derived relation as asingle operand applies nor only to the retrieval of data but also to theinsertion, update, and deletion of data.
• Physical Data Independence Application programs and terminal activities remain logically unimpairedwhenever any changes are made in either storage representation or accessmethods.
• Integrity Independence Integrity constraints specific to a particular relational database mustbe definable in the relational data sublanguage and storable in thecatalog, not in the application programs.
• Distribution Independence The data manipulation sublanguage of a relational DBMS must enableapplication programs and terminal activities to remain logicallyunimpaired whether and whenever data are physically centralized ordistributed.
• Nonsubversion Rule If a relational system has or supports a low-level(single-record-at-a-time) language, that low-level language cannot beused to subvert or bypass the integrity rules or constraints expressedin the higher-level (multiple-records-at-a-time) relational language.