SQL - Structured Query Language

INTRODUCTION:

SQL is a database computer language designed for managing data in Relational Data Base Management System(RDBMS). Its scope includes data insert,query,update,delete,creation,modification and data access control.

SQL was developed at IBM by Donald D.Chamberlin and Raymond F.Boyce in the early 1970's.
This version, initially called SEQUEL(Structured English QUEry Language), was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system.

The RDBMS was developed at MIT in the early 1970's, soon developed by Ingres,developed in 1974,who implemented query language is known as QUEL.which was later supplanted in the market place by SQL.

SQL statements that are specific to Oracle. Oracle offers a comprehensive high performance infrastructure for a e-business. It is called Oracle9i. Oracle9i includes everything needed to develop,deploy and manage internet applications.

Benefits Of Oracle9i:

• Scalability from departments to enterprise e-business sites.
• Robust and Reliable.
• Available and Secure architecture.
• Easy to learn
• Leverage an organization's current skillset throughout the Oracle platform(Including SQL,PL/SQL,JAVA, and XML)
• One management interface for all applications.

Oracle9i Database:

The roles of the two products are very straightforward. It manages all your data . This is not just the object relational data that you expect an enterprise database to manage. It can also be unstructured data like:

• Spreadsheets
• Word Documents
• Power Point Presentations
• XML
• Multimedia data types like MP3,Graphics,Video and more.

The data does not even have to be in the database.It has services through which you can store meta-data about information stored in the file systems. You can use the database server to manage and serve information wherever it is located.

Storing Information:

Every organization has some information needs. For example,a company needs to save information about employees,departments and salaries.These pieces of information are called data.
All the data's are stored in database. A database is an organized collection of information.To manage databases, you need database management systems(DBMS). A DBMS is a program that stores,retrieves and modifies data in the datebase on request.

These are four main types of databases:

• Hierarchial
• Network
• Relational
• More recently Object Reletional.

Relating Multiple Tables:

• Each row of data in a table is uniquely identified by a primary key(PK).
• You can logically relate data from multiple tables using foreign keys(FK).

Guidelines for Primary keys and Foreign keys:

• You cannot use duplicate values in a primary key.
• Primary keys generally cannot be changed.
• Foreign keys are based on data values and are purely logical,not physical,pointers.
• A Foreign key values must match an existing primary key value or unique key value,or else be Null.
• A Foreign key must reference either a primary key or unique key column.

SQL STATEMENTS:
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SELECT = = = = = = = = = Data Retrieval

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INSERT
UPDATE
DELETE = = = = = = = = =Data Manipulation Language(DML)
MERGE
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CREATE
ALTER
DROP = = = = = = = = = = Data Definition Language(DDL)
RENAME
TRUNCATE
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COMMIT
ROLLBACK = = = = = = = Transaction control
SAVEPOINT
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GRANT
REVOKE = = = = = = = = Data Control Language(DCL)
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