1832365
Mind Map by MegzRevision, updated more than 1 year ago
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Created by MegzRevision
about 5 years ago
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Description
Resource summary
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