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Chapter 5
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ICT Mind Map on Chapter 5, created by green.george on 10/04/2013.
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green.george
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green.george
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Resource summary
Chapter 5
Database components
Table - data structured into rows and columns requires a primary key
Records - a single row within a table made up of individual fields
Field - An individual data item within a record
Key - a field used for identification
Primary - allows a record to be uniquely identified. Can be combined to make a composite key
Secondary - a field which can be used to index data
Foreign key - a field which is linked to the primary key in another table or entity
Entity - A Thing which can be identified, a logical or physical storage unit
Relationships
One-to-one
One instance of X to one instance of Y
Uncommon
One-to-many
Common
One instance of X relates to many instances of Y
Many-to-many
Foreign key on many side and primary on the one
Many instances of X relate to many instances of Y
Normalisation
1NF
Primary key
Unique field names
no repeating fields
Atomic fields
3NF
All 2NF conditions met
All non-key fields are dependent on the primary key
2NF
All 1NF conditions met
All of the non-key attributes can be found using the primary key
Data dictionary
Defines aspects of a database
e.g. Table name Keys Relationships
Queries
Static - Predefined parameters
Dynamic - Parameter input on each run
Simple - Only one parameter
Complex - multiple parameters
AND
OR
NOT
*xyx*
x* (starts)
*x (ends)
Standard mathematical operators
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