Databases

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What is a flatfile database?
Information is held in a single table. Attribute - column. Row - record
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Why use a flatfile database?
For small amounts of data as it is simple and effective.
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Disadvantages of flatfile;
Large amounts of data stored can cause data redundancy
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What is data redundancy?
When data is replicated in a database
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Disadvantages of data redundancy;
In accurate data can cause legal issues e.g. Data protection act - data must be up to date
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What are relational databases?
Linked groups of small tables which use primary and foriegn keys.
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what are primary keys
uniques identifier in a table
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What are Foreign keys?
any field in a table which is the primary key in another
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What are secondary keys?
additional keys used to search for a record in a database
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Benefits of relational databases;
Remove problems formed from flatfile databases. Repetition is removed
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What is normalisation?
The process of converting a flat file database to a relational database
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What is indexing?
A data structure used to shorten the length of time it takes to search for information in a database
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Requirements for first normal form?
All attributes in a table are dependent on primary keys, each attribute contains only one piece of data.
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Requirements for second normal form?
No partial dependencies occur
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Requirements for third normal form?
No transitive dependencies (where A is dependent on B which is dependent on C therefore A is transistively dependent on C)
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Card 2

Front

Why use a flatfile database?

Back

For small amounts of data as it is simple and effective.

Card 3

Front

Disadvantages of flatfile;

Back

Preview of the front of card 3

Card 4

Front

What is data redundancy?

Back

Preview of the front of card 4

Card 5

Front

Disadvantages of data redundancy;

Back

Preview of the front of card 5
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