Databases
- Created by: frankie306
- Created on: 16-04-15 14:14
View mindmap
- Databases
- Persistant + organised store of data
- organisations
- loyalty card
- what they are selling
- entity
- a real world object about which data is stored
- corresponds to tables in the database
- stored in a database
- name
- attributes
- field name
- what the field contains
- first_name
- foreign key
- links a primary key to another table
- not unique
- avoids data redundancy
- otherwise data has to be changed every time
- primary key
- unique identifier
- no 2 things can have the same
- query
- question asked to a database
- AND
- OR
- NOT
- types
- electronic
- excel
- simms
- access
- paper
- diaries
- address book
- electronic
- levels of view
- external
- what the user sees
- conceptual
- how tables are linked/ organised
- physical
- the code
- how data is stored on the storage medium
- external
- flat file
- single table
- set up in a spreadsheet
- most common
- simple requirements
- address book
- heirarchal
- when more than one table is in a database
- validation
- sensible not correct
- presence check
- ensures that data has been entered
- length check
- no of characters
- range check
- acceptable range of values
- type check
- type of data
- format check
- desired format
- picture check
- input mask used
- DBMS
- database management systems
- create, maintain and interrogate a database
- physical data
- software
- allow data sharing
- allow multiple user access
- multiple apps to work
- hold one copy of data that everyone can access
- prevents inconsistent updates
- provides multiple views
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