Databases
- Created by: dairebreen
- Created on: 13-11-17 10:34
View mindmap
- Databases
- Relational Databases
- Data is stored in tables
- consisting of records
- Tables are linked
- Primary keys
- Foreign keys
- Normalisation
- Data redundancy minimised
- less storage required
- Data inconsistency minimised
- improves data integrity
- Data redundancy minimised
- Definitions
- Attribute
- each data item within an entity
- Entity
- an object about which information is stored
- Primary Key
- uniquely identifies a record
- Composite Key
- a key made up of more than one field
- Foreign Key
- a link between two tables,
- an attribute in one table but a primary key attribute in another
- Relationships
- a link between two entities
- linked together by pointers stored in the database
- Referential Integrity
- a feature that prevents users entering inconsistent data
- Data Duplication
- duplicate copies of data
- watses storage space and makes data redundant
- Data Inconsistency
- an attribute has more than one value
- stored in more than one table
- Attribute
- Relational Databases
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