36669092
Description
Flashcards by Malachy Moran-Tun, updated more than 1 year ago
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| Question | Answer |
| What is an Entity? | A category of object, person, event, or thing of interest to an organisation, about which data is to be recorded |
| What are Attributes and Records? | > Attributes - columns of the whole table (entity) > Records - rows of the whole table |
| What is a Flat File Database? | > Consists of a single file > Suitable to store one entity, e.g., a list of aname > Repeated data makes them inefficient > Unsuitable for more than one entity and their relationships |
| What is a Primary Key? | > Identifyer required for each entity in a database > Usually a numeric key for each record |
| What is a Secondary Key? | Used as an alternative index that is easier to know, e.g., a surname rather than a number |
| What are the 3 Types of Relationships between Entities? | > One-to-One > One-to-Many > Many-to-One |
| What is a Foreign Key? | > Attribute that joins two tables > Common to both tables - primary key in one, foreign in another > Allows for relationships between tables |
| How are Tables Linked in Many-to-Many Relationships? | > Additional table is created, containing just both primary / foreign keys > Both keys in the one table count as a "composite primary key" |
| What is Referential Integrity? | > Keeping shared / required attributes in databases > Shared attributes are not deleted on only one entity, in order to maintain the relationship |
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