Databases
Folien in diesem Satz (6)
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- Key Vocabulary
- database
- key field
- record
- field
- relational databases
- primary key
- foreign key
- data integrity
- reports
- digital data
- analogue data
- query
- data types (e.g. number, alphanumeric...)
- field properties (e.g. field size, input mask...)
- Bildunterschrift: Database: E.g. relational database
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- DATABASE- a collection of information which is structured in the same way to permit manipulation and searching data
- Why are databases used?
- data consistency - when data is updated on it is up-to-date for any application which uses the database
- data duplication - reduces to a minimum since only one copy of each data item needs to be kept
- easy to expand the database
- security of data is easier to monitor and maintain
- Bildunterschrift: data consistency / up-to-date for any application
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- Bildunterschrift: Data access can be controlled by database FRONT ENDS; the actual database won't be seen by other users except the database administrator
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- Data is often stored in FILES, which consist of RECORD, which in turn consist of FIELDS
- KEY FIELD - contains and item of data that is unique to that record; so no records have the same value in the key field
- RECORD - composed of fields, each containing one type of information
- FIELD - a space allocated for a particular item of information
- Bildunterschrift: Data Structure
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- RELATIONAL DATABASE - it consists of a number of separate tables which are related
- PRIMARY KEY - a combination of columns that are designated to uniquely identify all table records
- Advantages :
- they do not need to repeat data
- information is stored in separate tables only connected by the primary key field
- faster data retrieved (because of links between tables)
- easy expansion
- DATA INTEGRITY - all other references to this data will be up-to-date by only editing one table
- Bildunterschrift: relational database