Database Basics

Basic Concepts and Definitions

Database Defined

• A database is an organized collection of logically related data.

• Databases can vary significantly in size and complexity.

  • Small database: A salesperson's customer contact list (megabytes).
  • Large database: A corporation's database (terabytes).
  • Very large data warehouses: Contain petabytes of data.

Database Size

• Megabyte: Small Database for salesperson's customer contacts.
• Terabyte: A trillion bytes; example: Corporation's mainframe computer for decision support.
• Petabyte: A quadrillion bytes; example: Very large data warehouses.

Data and Its Types

• Assumption: All databases are computer-based.

• Historically, data referred to facts concerning objects and events recorded on computer media.

  • Example: Customer name, address, and telephone number in a salesperson's database.

Structured Data

• Numeric, character, and dates are the most important structured data types.
• Stored in tabular form: tables, relations, arrays, spreadsheets.
• Common in traditional databases and data warehouses.

Unstructured Data

• Includes documents, emails, tweets, Facebook posts, GPS information, maps, photographic images, sound, and video segments.
• Example: A photo image of a customer contact or a video clip about the most recent product.

Multimedia Data

• Structured and unstructured data combined, creating a true multimedia experience.

  • Example: An automobile repair shop combining customer and automobile data with images of damaged autos and scanned insurance claim forms.

Big Data Implications

• Big data technologies can handle highly heterogeneous data.

Expanded Definition of Data

• A stored representation of objects and events that have meaning and importance in the user's environment.