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Database & Data Modelling


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database
A collection of data organized in a manner that allows access, retrieval, and use of that data.
Database management system
a system software component that manages and controls one or more databases
Relational database management system
a DBMS that organizes data in tables (relations)
Table
A database view of information arranged in a grid of rows and columns
Row
one horizontal group of data attribute values
attribute
A characteristic of an entity or object. An attribute has a name and a data type.
Attribute value
the value held in a single table cell
Referential integrity
a consistent state among foreign key and primary key values
Normalisation
a formal technique for evaluating and improving the quality of a relational database schema
First normal form (1NF)
restriction that all rows of a table must contain the same number of columns (No Repeating attributes)
Functional dependency
a one-to-one association between the values of two attributes
SQL
__________ is the standard language for inserting, updating, and deleting data in a database
RDBMS
relational database management system
Team
List the tables you might need to store a database on a football League
Name: string
For a social networking site, what attributes and data types would you include for the table of people
What is a Primary Key?
is a field in a table that contains unique data.
Registration number
Convertable: Boolean
Composite key
Collection of attributes uniquely identify a tuple rather than just one
vehicle ---< wheel
A vehicle has many wheels, each wheel has one vehicle
Draw the relationship between a house and a postcode
House >--- Postcode (a house is assign one postcode, but that same postcode might be assigned to many houses)
What is meant by Third Normal Form?
(relation) contains no repeating groups of attributes /or/ data is atomic
Eliminates update anomalies
Why is it important that the relations in a database are in Third Normal Form?
SELECT name, DoB FROM crooks
Write an SQL statement that selects the names and dates of birth of male crooks with less than 3 scars.
UPDATE crooks
Write an UPDATE statement to change Geoff's age to 17/12/1939
DELETE FROM crooks
The police have agreed an amnesty with all heavily scarred (4+) women and have decided to delete them from the database. Write a statement to do this.
What is a Foreign Key
a column (or columns) that references a column (most often the primary key) of another table. The purpose of the foreign key is to ensure referential integrity of the data. In other words, only va…
What is an entity?
a person, place, thing or concept about which data can be collected. Examples include EMPLOYEE, HOUSE, CAR
Describe the process of Data Modelling
this involves designing the entities, attributes & entity relationships when setting up a database