Computer Concept week5_2

26/02/2010


Different type of database

• Flat file: Made up of a single table
  
• Relational: Maintain a set of set of separate, relate files(tables), but combines data elements using queries
• 
  
  Hierarchical: Structured in a hierarchy
  • Pros: fast, simple Cons: inflexible
• Network: Allow for data relationships in a net-like form
• Object Oriented: Managed by an object oriented database management system (ODBMS)

Database operation

• Amend: modify
  
• Insert: add
• Delete: remove
• 
  
  Retrieve: bring up
  
  

Data Structure: organized way of storing data that also defines how the data will be processed.

• Array: Series of memory locations using the same name
  
• Queue: First in First out(FIFO). The first element added to the queue will be the first one to be removed.
• 
  
  Stack: Last in First out(LIFO). The push and the pop.
  • Ex. Undo of Web browser
• 
  
  List: A list or sequence is a data structure.
  • Ex. Shopping Curt
• 
  
  Tree: Each element is attached to one or more elements directly beneath it.
  
  

Type of Data Access

Serial/Sequential

Records are accessed one by one.

Ex. cassette

Relative/Direct/Random

Information is stored containing details of the location of the file.

Ex. Record

Index Sequential

Records are accessed either sequential or randomly with an index.