Relational Database OR Relational Model-(Part-3) Relations – Let A1, A2,….,An be the attributes with domains D1, D2, …, Dn. A relational schema R consists of set of attributes with their corresponding domains. A relation r is a set of n tuples(A1:d1, A2:d2, …, An:dn) such that d1 ε D1, d2 ε D2,…, dn ε Dn. We write the…

Data Model in DBMS A model is an abstraction process that represent essential features without including the background details or explanations. It hides superfluous details while highlighting details pertinent to the application at hand. A data model is a mechanism that provides this abstraction for database applications. Data modelling is used for representing entities of…

Relational Model or Relational Database – (Part 1) The relational model is a lower level model. It is based on the concept of a relation, which is physically represented as a table. A table is a collection of rows & columns . The relational model uses a collection of tables to represent both data and the relationships…

Database Schema and Database Instance – Relational Model (Part2) Database Schema – Database Schema is the overall Design of the Database. It is the skeleton structure that represents the logical view of the entire database. It tells how the data is organized and how the relations among them are associated. It is sometimes also referred to as…

Network Database or Network Model in DBMS The network database or network model uses the plex structure as its basic data structure. A network is a directed graph consisting of nodes connected by links or directed arcs. The nodes corresponds to record types and the links to pointers or relationships. All the relationship are hardwired or…

ER MODEL (Entity Relationship Model) – Part-1 Before define ER Model, there are some terms which is require to understand ER model properly. In short, ER Model is a diagrammatic representation of entire Database tables. It represents a High Level Database Design. For Designing the Softwares : This phase is done in softwares by UML (Unified Modelling…