UNIT 1 CONCEPTUAL DATA MODELING

Traditional File Based Approach:

  1. Data Stored in Files
  2. Limitations:
    1. Data Duplication - Each program stores it own copy of files
    2. Data Inconsistency - Same data at different places need to be updated everywhere
    3. Data Security - Difficult to implement
    4. No Concurrency
    5. Searching takes time

Shared File Approach:

  1. Files shared between applications
  2. solves data duplication and inconsistency

DATABASE MANAGEMENT SYSTEM:

  1. DATABASE: Collection of Related Data
  2. DBMS: Software system used to create and manage databases

DB SYSTEM ENVIRONMENT:

  1. Components:
    1. Collection
    2. storage
    3. management
    4. access control
  2. SQL - Structured Query Language, Relational DB based e.g. MySQL, PostgreSQL
  3. NoSQL - Not relational DB e.g. MongoDB
  4. Access Languages
    1. DDL - Database Design Languages
    2. DML - Database Manipulation Language
      1. Procedural
      2. Non Procedural

DBLC

  1. Stages in implementing a database
  2. Stages:
    1. Requirements analysis:
      1. involves identification of problem and information needs to design a DB
    2. Logical design:
      1. 1st Conceptual Design is created, an ER - entity Relationship Diagram or description of structure of DB
      2. ER - Shows tables , fields, keys and relationships of DB
      3. The tables are then normalized to reduce redundancy
      4. Problems to avoid
        1. redundancy - repeated information
        2. incompleteness - bad design is impossible to model
    3. Physical design
      1. Maximize efficiency by finding ways to speed by Reading and writing to DB
    4. Implementation
      1. ER converted into tables which are converted into SQL Statements executed on RDBMS to create a DB
    5. Monitoring, Modification and maintenance
      1. Data Security, monitoring is done here
      2. Modification involves addition and deletion of records and creating additional tables

ER MODEL