Summary ORACLE CLASS NOTES

Definitions : Data : Data is considered as accurate and reliable facts. A fact may be text, number, sound, picture etc. Eg: A salesman maintains their customer’s address, phone number of all their customers. These facts are called as data. Information : When the data is organized into a meaningful format, at that point it becomes information. Database : It is a system which is designed to meet the information requirement of people at different levels with in the organization. (Or) It is a place where we keep the data permanently on the secondary storage device during the application process. Note : Any information system has 2 important components. 1) Software 2) Data DBMS (Data base Management System) : It is a software which allows the user to access the information from the data base. The objective of DBMS is to provide a convenient and efficient methods for adding, modifying, removing and distributing the data. Entity : It is a basic building unit to construct the database and it represents real world objects. Eg : A student in a college. Entity set : A group of similar interrelated set of objects are considered as entity set. Entity set is also called as relation(RDBMS), or table(oracle). Attribute : It is a property of the entity set. At the time of adding attributes to the entity set, we should take care whether it is useful or not to the organization. Attribute is also called as column or field or port. Attribute value : It is a value allowed to stored into appropriate attribute. Domain : A set or list or values which are permitted to store into the attribute. Eg : Marks of student is permitted between 0 and 100 are known as domain, negative marks and marks greater than 100 are not allowed. Types of attributes : 1. Simple attributes 2. Composite attributes 3. Single value attributes 4. Multi value attributes 5. Derived attributes Simple attributes : If the attribute is not possible to divide into sub parts is called as simple attributes. Eg : Rollno, Pincode, etc Composite attributes : If one attribute is possible to divide into sub parts is called as composite attributes. Eg : Name, Address etc. Single value attributes : If the attribute is used to identifying one particular instance in database is called as single value attribute. Eg: Emp no, Account number, Roll no etc. Instance Multi value attributes : If the attributes allows more than one type of value Eg: Course, Telephone number which allows multiple values as land number, mobile number etc. Derived attributes : If one attribute value depends on another attribute is called as derived attributes. Here existing attribute in database is called as stored attribute and new one is called as derived attribute. Eg : 1. Age(derived attribute) depends on data of birth(stored attribute) 2. Experience(derived attribute) depends on data of joining(stored attribute) Data base : A data base is an electronic collection of information designed to meet a handful of needs. Data base must provide mechanism to retrieve data quickly as applications interact with their contents. RDBMS : Relational Data Base Management System To be able to function, an organization needs information, example list of books in a library, customer details in retail business. A major requirement of any computer system is to store and retrieve data in a way that is meaningful to the end user. So the core of any information system is data, which is to be transformed into information through data modeling. The DBMS is the software and collection of tools that manages the data base. A RDBMS is a data base management system that based on the relational model. The objective of RDBMS is to achieve normalization of data, that reduce the redundancy(duplication of same data at different locations) A RDBMS is a computer program, which provides the user the facility to store and retrieve data in a manner consistent with a defined model, called the Relational model. The Relational model has 3 components. 1) Relation (Table) 2) Attributes (Columns) 3) Tuples (Rows) The RDBMS data are represented using tables (relations) A table is uniquely identified by its name and consists of rows that contain the stored information, each row containing exactly one tuple (record). A table can have one or more columns. A column is made up of column name and a datatype and it describes an attribute of the tuples. The structure of a table, also called relation schema, that is defined by its attributes. The type of information to be stored in a table is defined by the data types of the attributes at table creation time. SQL uses the terms table, row and column for relation, tuple, and attributes respectively. In 1977, Larry Ellison, Bob Miner and Ed Oates formed a company called Relation Software Incorporation (RSI). This company built an RDBMS called Oracle. RDBMS provide a simple way to think and analyzes the data used in business, it converts the business data into useful form of information. So ORACLE is an RDBMS product, it also convert the data into information and it follows the in/keep/out approach to maintain enterprise data in a more consistent manner. Oracle store the data which is intended to organization in an appropriate format, perform the operation if necessary to modify the existing data or to generate the reports and retrieve the required information form the data base to its users based on their requests. SQL : Structured Query Language SQL is the fundamental access tool of the oracle data base; in fact it is the fundamental access tool of all relational data bases. SQL is used to build data base objects and it is also used to query and manipulate both these objects and the data they may contain. Oracle provides SQL* plus, a SQL tool that enables us to interact with the data base.  It is simple English oriented grammatical language.  It is very easy to learn and implement.  It is not case sensitive.  Need not require any prior programming knowledge. Statements in SQL :