DBC 1

• Databases


  Make data persistent and shareable in a secure way
• Databases


  • Allow computer-based systems to store, manage, and retrieve data very quickly
• Raw data


  Facts that have not yet been processed to reveal their meaning
• Data


  Raw facts and figures that do not have any meaning until processed and given a context
• Information


  Produced by processing data and reveals the meaning of data
• INFORMATION = DATA + CONTEXT + MEANING
• Database


  A very large shared, integrated computer structure that stores end user data (raw facts) and metadata (data about data)
• DBMS (Database Management System)


  Makes data management more efficient and effective, and enables data to be shared among multiple applications or users
• Role of the DBMS

  • Enables data to be shared, presents the end user with an integrated view of the data, acts as an intermediary between the user and the database
• Advantages of the DBMS

  • Improved access to well-managed data for end users
  • Decreased data inconsistency risk
  • Enables fast ad hoc query responses
• Types of Databases by number of users

  • Single-user database (desktop database)
  • Multiuser database (workgroup databases, enterprise database)
• Types of Databases by location

  • Centralized database
  • Distributed database
  • Cloud database
• Types of Databases


  • Transactional
  • Data warehouse
  • Manual file system
• Structural dependence


  Access to a file is dependent on its own structure
• Structural independence


  File structure is changed without affecting the application's ability to access the data
• Problems with File System Data Management

  • Time-consuming, high-level activity
  • Making changes in existing file structure is difficult
  • As number of files expands, system administration becomes difficult
• Data redundancy


  The same data are stored unnecessarily at different places
• Problems caused by uncontrolled data redundancy

  • Data inconsistency
  • Poor data security
  • Data anomalies
• Types of data anomalies

  • Update anomalies
  • Insertion anomalies
  • Deletion anomalies
• Database system components


  • Hardware
  • Software
  • People
  • Procedures
  • Data
• DBMS Functions

  • Multiuser access control
  • Backup and recovery management
  • Data integrity management
• Data modeling


  An progressive process to create a model for a problem domain
• Data models


  Simplify complex data structures to support specific domains, abstract real-world objects or events
• Importance of Data Models

  • Are a communication tool
  • Give an overall view of the database
  • Organize data for various users
• Data Model Basic Building Blocks

  • Entity
  • Attribute
  • Relationship
  • Constraint
• Relationship Types


  • One-to-many (1:M)
  • Many-to-many (M:N or M:M)
  • One-to-one (1:1)
• Hierarchical Model


  • Promotes data sharing, efficient with 1:M relationships, database security is provided and enforced by DBMS
• Network Model


  • Data access is flexible, conceptual simplicity, handles more relationship types
• Data manipulation language (DML)


  Environment in which data can be managed and is used to work with the data in the database
• Schema data definition language (DDL)


  Enables the database administrator to define the schema components
• Relational Model


  • Isolates the end user from physical-level details, tabular view improves conceptual simplicity
• Relational Database Management System (RDBMS)

  Performs basic functions provided by the hierarchical and network DBMS systems
• SQL-Based Relational Database Application

  • End-user interface allows end user to interact with the data, collection of tables stored in the database, SQL engine executes all queries
• Entity relationship diagram (ERD)


  Uses graphic representations to model database components
• Entity instance or entity occurrence

  Rows in the relational table
• Connectivity


  Term used to label the relationship types
• Object-Oriented Data Model (OODM)


  • Object contains data and their relationships with operations that are performed on it, class is a collection of similar objects with shared structure and behavior organized in a class hierarchy, inheritance allows objects to inherit methods and attributes of parent class
• Unified Modeling Language (UML)


  Describes sets of diagrams and symbols to graphically model a system
• Big Data


  Characterized by volume, velocity, and variety
• External Model


  End users' view of the data environment