igcse ict ao2.5 notes

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  • Created on: 11-05-13 19:32
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AO2.5 Data types
A. identify different data types: logical/Boolean, alphanumeric/text, numeric (real and integer) and date
B. select appropriate data types for a given set of data: logical/Boolean, alphanumeric/text, numeric
and date
C. describe what is meant by the terms file, record, field and key field
D. describe different database structures such as flat files and relational tables including the use of
relationships, primary keys and foreign keys
E. state the difference between analogue data and digital data
F. explain the need for conversion between analogue and digital data

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Analogue Digital
Analogue is used to describe something that Digital means having only discrete values, as
changes value smoothly. It is the opposite of opposed to analogue which has continuously
digital which describes something that changing values.
changes in steps.…read more

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Currency/Numeric
(real)
Numeric
Alphanumeric/
Alphanumeric/ Alphanumeric/
(integer) text
text text
Alphanumeric/
Alphanumeric/ Alphanumeric/ Alphanumeric/
text
text text text
Key field Logical/Boolean
Field
record…read more

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Describe different database structures such as flat files and relational tables
including the use of relationships, primary keys and foreign keys
What is a flat file database?
Definition Example
A flat file database describes any of various
means to encode a database model (most
commonly a table) as a single file.
A flat file can be a plain text file or a binary file.
There are usually no structural relationships
between the records.…read more

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What are relationships?
Definition Example
We need to link the table you would get a relationship in Microsoft
together so that we can Access (database).
connect a student to a
specific tutor and room.
The common field in both
tables is the Class field.
We use this field to create a
relationship (link) between
the two tables...
Note that to create the
relationship, we are using
the key field (primary key)
from one table to link it to
another.…read more

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What are primary key fields?
Definition Example
It is very important that every record in a you would only find primary key fields in a
database can be individually identified. We relational database, not a flat file.
need to be sure that when we access a record,
we are accessing the correct one.…read more

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Relational and flat file databases:
Flat file databases are databases which are stored as a single table and can be created in
software such as Microsoft Excel or a Spreadsheet. In comparison, a relational database is
harder to create and maintain this is because they are usually made in a program such as
Access which is not the easiest to use.
Primary Key field and Foreign Key Fields:
Primary key fields are a unique piece of information which helps you to identify everything
else.…read more

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Which data type would you use?
1.
Field Data type
VIN alphanumeric
Model text
Power text
Engine Size alphanumeric
Price currency
Colour text
Location text
Sold boolean
Which would you choose to be the primary key field? VIN
2.…read more

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Data types vocab list
1. Sort the list by confidence. Put the most confident at the bottom of the list and the least confident at
the top.
2. Add an example then a brief definition.…read more

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