GCSE Computer Science: Database

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Mind Map by MegzRevision, updated more than 1 year ago
MegzRevision
Created by MegzRevision about 5 years ago
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Mind Map on GCSE Computer Science: Database, created by MegzRevision on 01/04/2015.

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GCSE Computer Science: Database
1 Entity
1.1 An entity is a person or physical thing about which data is held in a database
2 Field
2.1 An individual box in the data table
2.1.1 Table = The whole thing
3 Record
3.1 An entire row of data
4 Database management system / DBMS
4.1 Allows you to create a table
4.2 Componants
4.2.1 Tables
4.2.2 Forms
4.2.3 Queries
4.2.4 Reports
4.2.5 Modules
4.2.5.1 Program within an application that performs a specific task which cannot be done by simply making a query or report
5 Datatypes
5.1 Text
5.2 Integers
5.3 Numbers with a decimal
5.4 Dates
5.5 Currency
5.6 Yes/No fields
6 Primary Key
6.1 One field is designated as the p.k
6.2 Each record must have a different value in the p.k
6.3 Uniquely identifies the record
7 Validating Fields
7.1 Minimise errors when data is entered into the database
7.2 Specifying a rule that the data must obey
7.2.1 Range check
7.2.2 Type check
7.2.2.1 e.g. number
7.2.3 Presence check
7.2.3.1 Data entered in the field
7.2.4 Format check
7.2.5 List check
7.2.5.1 Must be item on predefined list
8 Data Redundancy
8.1 Holding more data than necessary
8.2 Takes time and space
8.2.1 Can result in inconsistent data
8.3 Each entity has an attribute
8.3.1 Attribute = Field in the table which describes the entity
8.3.1.1 One-to-one
8.3.1.1.1 e.g. husband/wife
8.3.1.2 One-to-many
8.3.1.2.1 e.g. mother/children
8.3.1.3 Many-to-many
8.3.1.3.1 e.g. pupils/subjects
9 Separation of Data
9.1 Data held about various entities are held separatly from the applications that use it.
9.1.1 e.g. many departments in a school can look at or use the data
9.2 Reduces data redundancy
9.3 Data is consistent
9.4 Saves storage
10 Database
10.1 Persistent, organised store of data
10.1.1 Persistent = Data stored on a non-volatile storage device
10.1.2 Organised = Structured into tables
10.2 Allows separation of data between applications and the database
10.3 Allows multiple applications to use a single database
10.4 Can allow many users to simultaneously access the data and it's applications
10.5 Provides security in terms of access rights
10.6 Can provide automatic backups
11 Reports
11.1 Useful feature of a DBMS
11.2 Reports are produed based on queries
11.3 When a user asks for a report based on a query, the query will automatically be run first using the latest data, so the report is up-to-date
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