RELATIONAL DATABASE

• METADATA

  -         Descriptions of the properties or characteristics of data.

  -        like data types, field sizes, allowed values, and documentation.

  
• TRADITIONAL FILE PROCESSING (TFP)

  -         Data are stored for each individual application in an organization

  -         Each department within an organization  has its own set of files. Often creating data redundancy and data isolation.

  -        No overall map, plan, model guided application growth

  
• DISADVANTAGE OF TFP

  a.    DUPLICATION OF DATA

  o    Inefficient use of storage space

  o   data integrity may be compromised
• DISADVANTAGE OF TFP

  b.    PROGRAM DATA DEPENDENCE

  o   Excessive program maintenance

  o   Lengthy development of program
• DISADVANTAGE OF TFP

  a.    LIMITED DATA SHARING

  o  No centralized storage of data
• THE DATABASE APPROACH

  -         Data are logically stored in databases, managed by a database management system.

  -         Designed using data models which define nature and relationships among data

  -         The effectiveness and efficiency of a database is directly associated with the structure of the data base.
• DATABASES CONTENTS

  -         To make database design more straightforward
• TWO CONCEPTS OF DATABASE CONCEPTS

  A.   SCHEMA – structure of the data indicates“the rules” which the data must obey.

  B.    DATA – are the FACTS.
• CHARACTERISTICS OF DBMS APPROACH

  1.     SELF-DESCIBING NATURE OF A DATABASE SYSTEM

  -         Database System: database + metadata

  (Metadata is stored in DBMS catalog, and is used by DBMS Software & Database Users

  -         DBMS Software must work equally well with any number of database applications

  -         In TFP, data definition → part of application programs → work with only one specific DB.
• CHARACTERISTICS OF DBMS APPROACH

  2.  INSULATION BETWEEN PROGRAMS AND DATA, AND DATA ABSTRACTION

  -         In TFP → structure of data files is embedded in the application programs.

  -         In DB Approach → structure of data files is stored in the DBMS catalog → separate from access programs (program-data independence)

  -         The characteristic that allows program-data independence is called data abstraction.

  -         DBMS provides users with conceptual representation of data

  -         Data model → type of data abstraction → provides conceptual representation
• CHARACTERISTICS OF DBMS APPROACH

  3.   SUPPORT OF MULTIPLE VIEWS OF THE DATA

  -         A database has many users, each of whom may require a different view of database.

  A view → subset of database → contains virtual data derived from database (not explicitly stored
• CHARACTERISTICS OF DBMS APPROACH

  4. SHARING OF DATA AND MULTIUSER TRANSACTION PROCESSING

  -         A multiuser DBMS allows multiple users to access the database at the same time.

  -         DBMS must include concurrency control

  (Concurrency control prevents two users from editing the same data at the same time)

  -         OLTP (Online Transaction Processing) → major part of database application

  -         DBMS must enforce several transaction properties: i. isolation and ii. Atomicity
• TYPES OF DATABASES

  1.     RELATIONAL DATABASES

  2.    NON-RELATIONAL DATABASES (NO SQL)

  3.    OBJECT-ORIENTED DATABASES (OOD)
• TYPES OF DATABASES

  1.     RELATIONAL DATABASES

  -         Store data in tables of rows and columns, where each row is record and each column is an attribute
• TYEPS OF DATABASES

  2.   NON-RELATIONAL DATABASES (NO SQL)

  -         Use query languages or third-part APIs instead of SQL and store data in diverse formats, such as documents, graphs, key-value pairs, or columns.
• TYPES OF DATABASES

  1.     OBJECT-ORIENTED DATABASES (OOD)

  -         Store data as objects with attributes, classes and methods.

  -         The same concepts and principles as OOP languages (Python, Java, C++, Ruby, and JavaScript.
• ADVANTAGES OF DATABASE APPROACH

  a.    PLANNED DATA REDUNDANCY

  -         Minimal data duplication

  -         Improved data consistency

  b.    PROGRAM DATA INDEPENDENCE

  -         Allows data to evolve without changing the application programs

  -         Reduced program maintenance

  c.    IMPROVED DATA SHARING

  d.    INCREASED PRODUCTIVITY OF APPLICATION DEVELOPMENT

  e.    ENFORCEMENT OF STANDARDS

  f.      IMPROVED DATA QUALITY

  g.    IMPROVED DATA ACCESSIBILITY AND RESPONSIVENESS

  h.    IMPROVED DECISION SUPPORT
• RANGE OF DATABASE APPLICATIONS

  a.    PERSONAL DATABASES – supports one user

  b.    WORKGROUP DATABASES (less than 25 users) – supported by two-tier client/server databases

  c.    DEPARTMENT/DIVISON DATABASES (between 25 to 100 users) – supported by multitier client/server databases

  d.    ENTERPRISE DATABASES – scope is entire organization
• EVOLUTION OF DATABASES

  1970 – 1990 – HIERARCHICAL

  -         Data model in which data is organized into a tree-like structure; one to many relationship
• EVOLUTION OF DATABASES

  1970 – 1990 – NETWORK

  -         Much like the hierarchical model except it is permitted to many to many relationship.
• EVOLUTION OF DATABASES

  1980 – PRESENT – RELATIONAL

  -         establish the relationships between entities by means of common fields included in a file called a relation.
• EVOLUTION OF DATABASES

  1990 – PRESENT – OBJECT-ORIENTED

  -         subscribes to a model with information represented by objects; encapsulates both data and behavior.
• EVOLUTION OF DATABASES

  1190 – PRESENT – OBJECT- RELATIONAL

  -         provide a middle ground between relational databases and object-oriented databases.