BCA

 DATA MODEL It is a conceptual tools which describe logical design of a database. It define entity definations, relationship and symmentic properties of intigrity constant. The very first data model could be flat data-models, where all the data used are to be kept in the same plane. Earlier data models were not so scientific, hence they were prone to introduce lots of duplication and update anomalies.  While the  Relational Model  is the most widely used database model, there are other models too: Hierarchical Model Network Model Entity-relationship Model Relational Model Hierarchical Model This database model organises data into a tree-like-structure, with a single root, to which all the other data is linked. The heirarchy starts from the  Root  data, and expands like a tree, adding child nodes to the parent nodes. In this model, a child node will only have a single parent node. This model efficiently describes many real-world relationships like index of a book, recipes etc. In hierar

  ENTITY  An entity is a object which differenciate from another object in the real world. For eg:  employee,customer,doctor,patient all those are entity. Entity is a set of attribute.Attribute is a field which describe the description property of entity. A set of some type of entity is called  entity set. ROLE OF DBMS One of the main reason for having DBMS is to have control of both data and program execessing that data.The DBMS as a person or program having such control over thr system. The main role of DBA: 1.Schema defination The creation of the original database schema by writting a set of defination which are translated by the DDL compilar(Data Defination Language) to a set of table that are permanently stored in the data dictonary. 2.Storage Structure and access method defination. The creation of appropriate and excess method by writting a set of definitions which are translated by the data storage and defination language compiler. 3.Schema and Physical organisation modification

  DBMS (Database Management System) DBMS stands for Database Management System. We can break it like this DBMS=Database+ Management System. Database is a collection of data and management system is a set of programs to store abd retrieve those data. Based on this we can define DBMS like this: DBMS is a collection of inter-releted data and set of programs to store and access those data in an easy and effective those data in an easy and effective manner. The main characteristics of database system: 1.It provide to create, modify and remove the database. 2.To store new information, to change (update) existing information and remove(delete) information. 3.It provides data manipulation using mathematical and logical operator. 4.It provides to generate various report(permanentiy)/adhoc(temporary). 5.It provide data integrity. What is the need of DBMS? Database Systems are basically developed for large amount of data.When dealing with huge amount of data, there are two things that require opt