1.3.2

• Relational Database


  A database which recognises the differences between entities by creating different tables for each entity
• Flat File


  A database that consists of a single file, typically based around a single entity and its attributes
• Database components


  • Primary Keys
  • Foreign Keys
  • Secondary Keys
• Entity Relationship Modelling


  • One-to-one
  • One-to-many
  • Many-to-many
• Normalisation


  The process of coming up with the best possible layout for a relational database
• Types of Normalisation


  • First Normal Form
  • Second Normal Form
  • Third Normal Form
• Indexing


  A method used to store the position of each record ordered by a certain attribute, to look up and access data quickly
• Methods of capturing data

  • Manual entry
  • Magnetic Ink Character Recognition (MICR)
  • Optical Mark Recognition (OMR)
  • Optical Character Recognition (OCR)
• Selecting and managing data

  • Data preprocessing to reduce volume of input
  • Using SQL to sort, restructure and select data
• Exchanging data


  Transferring collected data, often using Electronic Data Interchange (EDI) which doesn't require human interaction
• SQL


  Structured Query Language, a declarative language used to manipulate databases
• SQL statements


  • SELECT, FROM, WHERE, ORDER BY
  • JOIN
  • CREATE
  • ALTER
  • INSERT INTO
  • UPDATE
  • DELETE
• Referential Integrity


  The process of ensuring consistency, so that information is not removed if it is required elsewhere in a linked database
• Transaction Processing


  • Atomicity
  • Consistency
  • Isolation
  • Durability
• Record Locking


  The process of preventing simultaneous access to records in a database, to prevent inconsistencies or loss of updates
• Redundancy


  The process of having one or more copies of data in physically different locations, to prevent data loss