Database

• record (table)- colllection of one or more feild value/attribute/data
• File - collection of one or more records (table)
• Feild (cells)- lowest level of data item of a record
  • data -> record -> file -> database

Advantages of Database System

• what are the Advantages of Database System?

  1. Redundancy Reduction

     • Eliminates duplicate data using Normalization.
     • Saves disk space and prevents inconsistency.

  2. Avoids Inconsistency

     • Ensures data remains consistent across applications.
     • Uses "Propagating updates" to synchronize multiple copies.

  3. Data Sharing

     • Supports concurrent access by multiple applications.
     • Distributed databases maintain mirror copies of data (e.g., railway reservations).

  4. Data Integration

     • Combines data from multiple tables to answer complex queries.
     • Example: Linking Student and Staff tables to retrieve results.

  5. Security Mechanism

     • Protects data using:
       a) Software Controls – Authentication (login/password), Encryption.
       b) Hardware Controls – Access cards for restricted areas.

  6. Integrity Maintenance

     • Prevents invalid data entry using integrity constraints.
     • Example: Ensuring HOURS_WORKED field accepts values between 0 to 24.

  7. Balancing Conflicting Requirements

     • Database Administrator (DBA) optimizes storage structures and access methods for efficiency.

  8. Data Independence

     • Logical Data Independence – Changing application code without modifying storage.
     • Physical Data Independence – Changing storage structure without modifying application code.