type of databases

type of databases

1. flat database

   • one table with all the database
   • disadvantages
     • more likely to be errors
     • it repeats the same information e.g. a postcode
     • waste time

2. relational

   • more than one table. links all the information together from different tables without repeating anything
   • advantages
     • save time
     • simple design. not mixing the data up
     • modification can be made easily
     • different levels of access
     • when changing something then it will change on the other table
   • features
     • information is spread into discrete entities
       • based on the real world
       • employee, product, order
     • entities are describe by a series of fields
       • describes the structure of the entities
       • product name, weight , prices
     • entities are connected by a series of relationships
       • built using common fields
       • represented by entity relationship diagrams (ERFs)

3. local

   • one person can use it/access it
     • what is needed
       • username
       • password

4. network

   • more people can use it/access it. But they can not change it because of the restriction level
     • what is needed
       • certain level of access
       • username
       • password

5. online

   • why they are used
     • so people can see an updated version
   • examples
     • Amazon
     • Tesco
     • eBay