Database Design and Development (Design)
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What are databases made of?
Databases are made of entities and attributes
Entities become tables during implementation. What are entities?
Entities are; a person a place an object a thing
Attributes become fields during implementation. What are attributes?
Attributes are characteristics of entities. Examples of attributes are; firstName lastName address etc.
What are Primary Keys (PK)?
Primary Keys are unique identifiers of entities
What are Foreign Keys (FK)?
Foreign Keys are what links two or more tables together
What is it necessary to show in databases?
Relationships between tables
What do data dictionaries do?
Data Dictionaries define the structure of the database
What do data dictionaries hold information on?
Data Dictionaries contain; Names of entities Names of attributes Data types of attributes Size of attributes Indication of PK's or FK's
What are the field types and what do they hold?
Text - holds any character/number Number - holds only numbers (but not telephone numbers) Boolean - True/False Date - stores dates Time - stores times
What are the four types of input validation?
Presence Check Restricted Choice Field Length Range
What is a Presence Check?
Presence Checks are pieces of validation which make any data in a field compulsory
What is a Restricted Choice?
Restricted Choice limits the amount options a user can input thus cutting down the number of execution errors
What is Field Length?
Field Length restricts the amount of characters a field can hold
What is Range?
Range makes sure that the numbers inputted are between two extremes
What are Queries?
Queries are ways of looking up certain data from a database
What do we state when making queries at this level?
Field(s) Table(s) Sort Order Criteria