AQA A LEVEL COMPUTER SCIENCE
2024 FULL EXAM PAPERS AND
MARK SCHEMES WITH ACCURATE
SOLUTIONS AND VERIFIED
ANSWERS GRADE A+
◉ Relational Database. Answer: A relational database is where the data
is held in more than one table, and the tables are linked together using
relationships.
◉ Data redundancy. Answer: occurs when unnecessary duplicate
information exists in a database
◉ Data inconsistency. Answer: When the data is not accurate, and lacks
integrity
◉ Why use a relational database and not a flatfile database. Answer:
Relational databases reduce data redundancy and increase data integrity
◉ Why use a flatfile database not a relational database. Answer: Flatfile
databases are used when there isn't that much information.
It is easy to set up
Relational databases take time to set up
Difficult to set up/use
,◉ Attribute (databases). Answer: The features of each entity (The
columns in a table)
◉ Record (databases). Answer: A set of data stored in a table (the rows
in a table
◉ Primary Key (database). Answer: The unique identifier of each
record.
◉ Foreign Key (database). Answer: A primary key of one table that
appears as an attribute in another table and acts to provide a logical
relationship between the two tables
◉ Composite Key. Answer: A multiple-attribute key.
◉ Why are databases normalised. Answer: Reduces data duplication,
and improves integrity
◉ Features of 1NF (First Normal Form). Answer: Each record has a
primary key
Data is atomic
No Repeating groups or Attributes
◉ Atomic data (databases). Answer: Atomic data is data that can't be
divided into smaller subparts. Eg. Name is not atomic as it can be
divided into surname and forename, but date of birth is atomic.
, ◉ Dependency (databases). Answer: A dependency is when one
attribute is dependent on another attribute. For example, "class ID" is
dependent of "class Name" as the class Name will have it's chosen
classID
◉ Features of 2NF (Second Normal Form). Answer: No partial
dependencies
therefore, no composite keys
Each record should have only one primary key.
◉ Features of 3NF. Answer: No Non-key dependencies
For example, if there is a "forename", "surname", and "email" attribute,
a new table must be created, as they are all dependent on each other
Make sure no non-key attributes depend on each other.
◉ Retrieving SQL. Answer: SELECT <attribute> FROM <table>
WHERE <condition> ORDER BY <asc/desc>
ORDER BY is optional (isn't always there)
A * is used to mean everything.
2024 FULL EXAM PAPERS AND
MARK SCHEMES WITH ACCURATE
SOLUTIONS AND VERIFIED
ANSWERS GRADE A+
◉ Relational Database. Answer: A relational database is where the data
is held in more than one table, and the tables are linked together using
relationships.
◉ Data redundancy. Answer: occurs when unnecessary duplicate
information exists in a database
◉ Data inconsistency. Answer: When the data is not accurate, and lacks
integrity
◉ Why use a relational database and not a flatfile database. Answer:
Relational databases reduce data redundancy and increase data integrity
◉ Why use a flatfile database not a relational database. Answer: Flatfile
databases are used when there isn't that much information.
It is easy to set up
Relational databases take time to set up
Difficult to set up/use
,◉ Attribute (databases). Answer: The features of each entity (The
columns in a table)
◉ Record (databases). Answer: A set of data stored in a table (the rows
in a table
◉ Primary Key (database). Answer: The unique identifier of each
record.
◉ Foreign Key (database). Answer: A primary key of one table that
appears as an attribute in another table and acts to provide a logical
relationship between the two tables
◉ Composite Key. Answer: A multiple-attribute key.
◉ Why are databases normalised. Answer: Reduces data duplication,
and improves integrity
◉ Features of 1NF (First Normal Form). Answer: Each record has a
primary key
Data is atomic
No Repeating groups or Attributes
◉ Atomic data (databases). Answer: Atomic data is data that can't be
divided into smaller subparts. Eg. Name is not atomic as it can be
divided into surname and forename, but date of birth is atomic.
, ◉ Dependency (databases). Answer: A dependency is when one
attribute is dependent on another attribute. For example, "class ID" is
dependent of "class Name" as the class Name will have it's chosen
classID
◉ Features of 2NF (Second Normal Form). Answer: No partial
dependencies
therefore, no composite keys
Each record should have only one primary key.
◉ Features of 3NF. Answer: No Non-key dependencies
For example, if there is a "forename", "surname", and "email" attribute,
a new table must be created, as they are all dependent on each other
Make sure no non-key attributes depend on each other.
◉ Retrieving SQL. Answer: SELECT <attribute> FROM <table>
WHERE <condition> ORDER BY <asc/desc>
ORDER BY is optional (isn't always there)
A * is used to mean everything.
