Karteikarten
Databases 4.10
Karten in diesem Stapel (10)
- 1DatabaseA Database is a persistent, organised store of data, organised for easy retrieval.
- 2DatabaseIn a database, data is stored in tables.
The simplest type of data uses only one table (essentially spreadsheet). This is called a flat-file database.
Each table contains a series of fields – categories of individual data items. - 3Flat file Example
- 4Limitations to flat fileData Redundancy: The same data is being entered over and over
Data Inconsistency: If a mistake is made on one of the entries, it can cause major issues. What type of car is the blue Ford?
Difficulty updating: Bob moved house, but his old records have the incorrect address. - 5Relational databaseMultiple tables linked together using keys
- 6primary keyA Primary Key is a field that contains a unique value for that record – no other records can have the same primary key.
- 7Relational Database
- 8entityAn Entity is a real-world “thing” about which data is stored in a database.
- 9RelationshipThere are three different types of relationships between entities
One-to-one
One-to-many
Many-to-many - 10Working out relationshipsView both sides to decide relationship
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- Beschreibung
- Karteikarten am Databases 4.10, erstellt von Ed Allen am 12/12/2019.
- Erstellt von
- Ed Allen · Dez 2019
- Aktualisiert
- 9 Mär 2020
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