Week 1

• Data


  A collection of facts, that are related to any person/object in consideration
• Database


  An organized collection of data, held in a computer, to generate knowledge for decision making purposes
• Database Management System (DBMS)


  A software package designed to enable users to create, store, manipulate data, etc, perform data backup, and to develop reports in a convenient and efficient way
• DBMS acts as an intermediary, users are not given direct access to the database, users can only access the database via a DBMS
• Database used in QUB


  • Students' academic records
  • Data about students, faculty, courses, course registrations, etc.
• QSIS


  The DBMS used for the database at QUB
• Flat-File model


  A simple consecutive List of Records, a slow way to search and maintain large volumes of records

  
• Flat-File model required computers to begin every search at the start of the list and to search sequentially, not good enough for a faster database system that are reliable and efficient
• Disadvantages of Flat File Model


  • Ad-hoc structures used for data storage and management
  • Limited Data Sharing
  • Basic Data Retrieval and Querying
  • Data redundancy
  • No concurrency
  • Limited Scalability and Performance
  • Ad-hoc Security measures
• DBMS Model


  • Centralised Data Management & Standardized Processes
  • Advanced Data Sharing and Accessibility
  • Sophisticated Data Retrieval and Querying
  • Robust Data Integrity
  • High Scalability and Performance
  • Integrated Security Measures
• 4 major types of DBMS data models


  • Hierarchical
  • Network
  • Relational DBMS data model
  • Object-oriented
• Relational DBMS data model


  It defines database relationships in forms of tables (relations), based on relations of mathematical set theory, uses structured query language (SQL) statements to manipulate data
• Schema


  The design/structure of our data, and how it is organised, what we store, and how those things are related
• DBMS (Database Management System)


  The software used to store the data, ideally in an efficient and robust manner (fast and reliable), examples are Microsoft Access, MySQL, MariaDB, Oracle, SQL Server, DB2
• Query Language


  The language (Domain Specific Language, DSL) used to manipulate the data (such as to create, read, update, delete) stored within a DBMS, example is SQL (Structured Query Language)
• Database


  An organised collection of data
• Enterprise-level DBMS


  • Have many tables
  • Have many databases
  • Involve multiple computers
  • Complex in design
  • Supports concurrency (several users access the database at the same time)
  • Supports more than one application
• DBMS (Database Management System)


  The software used to store the data, ideally in an efficient and robust manner (fast and reliable)
• Personal DBMS


  • Microsoft Access
• Enterprise-level DBMS


  • MySQL, MariaDB, Oracle, SQL Server, DB2
• Query Language


  The language (Domain Specific Language, DSL) used to manipulate the data (such as to create, read, update, delete) stored within a DBMS
• SQL (Structured Query Language)


  Example of a Query Language
• Enterprise-level DBMS


  • Have many tables
  • Have many databases
  • Involve multiple computers
  • Complex in design
  • Support concurrency (several users access the database at the same time)
  • Support more than one application
• The design/structure of our data, and how it is organised
• What we store, and how those things are related
• Components of a Database System: Users, Hardware, Software, Procedures, Data
• Conceptual Data Model


  Highest level of abstraction, focuses on the high-level description, useful for requirements understanding
• Entity-Relationship (ER) diagrams


  A tool to visualise conceptual designs
• Logical Data Model


  Describes how the conceptual schema is translated into a logical schema, with specifics about tables, columns, and keys, but without physical storage details
• Normalization


  Used to optimise the logical structure
• Data are organised into simple tables of related information, each table contains data about a different data theme (Entity), and the tables are connected only by having matching data fields</b>
• Database contains Metadata: data describing the structure of the data in the database
• Data dictionary


  Holds the metadata when a database is being designed
• Physical Data Model


  The logical model is translated into a physical model, includes decisions about the type of storage, the database system, and optimisation for performance