Please enable JavaScript.
Coggle requires JavaScript to display documents.
1.3.1 Databases (Flat file database (comprises of only one table, data…
1.3.1 Databases
Flat file database
comprises of only one table
data redundancy
data inconsistency
quick and easy
to make
fine for
small amounts of data
&
single-entity
models
Relational database
comprises of multiple tables
diff parts have links between them
duplication avoided by structuring data
minimises
database size
avoids
redundancy
Keys
primary
- unique values for each record
secondary
- different index to navigate through
foreign
- primary key of another table
used for links
compound
- combo of fields to uniquely identify record
Notation
ENTITY
(attributes)
key field
(bold/underlined)
e.g. COURSE_VENUE(
VenueID
, Name, Address)
Types of data
atomic- cannot be split further
redundant- same info repeated
inconsistent
Designing databases
attribute
- field being considered (column)
record
- row on database
entity
- table being considered
Checking methods
validation
- checking against rules
e.g. can't enter 'dog' as a phone no
verification
- checking it's correct
e.g. double entry when changing password