Summary DBMS - Database Management System In-class activity

DBMS - Database Management System In-class activity Database - Collection of Data Management System - a set of programs to store and retrieve data. DBMS - (Database Management System) A collection of inter-related data that contains programs to store & access that data in an easy and effective manner. What is the need of DBMS? - Store Data in an optimized and systematic manner and Retrieve Data Fast What are some Examples Applications where we use Database Management Systems are: - Telecom Industry Banking Education sector Online shopping Advantages of DBMS over a FILE System - no redundant data Data consistency and Integrity Secure Privacy Easy access to data Easy recovery Flexible Disadvantages of DBMS over FILE System - Higher implementation Cost Complexity Performance for some applications What must you have to understand the view of data? - Data Abstraction Instance and Schema What is data abstraction? - The process of hiding irrelevant details from user What are the 3 levels of Data abstraction? - Physical Logical View Physical abstraction level - This is the lowest level of data abstraction. It describes how data is actually stored in database. You can get the complex data structure details at this level. records can be described as blocks of storage (bytes, gigabytes, terabytes etc.) in memory. Logical abstraction level - - Middle level - Describes what data is stored in database - Developers and admins access this level. - records can be described as fields and attributes along with their data types, their relationship among each other can be logically implemented. View abstraction level - - Highest level of data abstraction. - Describes the user interaction with database system. user just interact with system with the help of GUI and enter the details at the screen, they are not aware of how the data is stored and what data is stored; such details are hidden from them. Database Instance - The data stored in database at a particular moment of time Database vs Instance - Database is the set of files where application data (the reason for a database) and meta data is stored. An instance is the software (and memory) that Oracle uses to manipulate the data in the database. Database Schema - Design of a database. Defines the variable declarations in tables that belong to a particular database; 3 Schema levels - Physical Logical View keys in DBMS - Used for identifying unique rows from table. Establishes relationship among tables. Types of keys - Primary Super Candidate Alternate Composite