The information for a large international company is stored in a database - NSC Information Technology - Question 4 - 2019 - Paper 2
Question 4
The information for a large international company is stored in a database.
4.1 A data capturer captures all organisational data.
4.1.1 Explain what the GIGO princi... show full transcript
Worked Solution & Example Answer:The information for a large international company is stored in a database - NSC Information Technology - Question 4 - 2019 - Paper 2
Step 1
Explain what the GIGO principle is.
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Answer
The GIGO (Garbage In, Garbage Out) principle states that the quality of data entered into a system directly affects the quality of the information that can be extracted. If the data is incorrect, then the output produced will also be incorrect.
Step 2
Name TWO types of checks to ensure that the captured data is valid.
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Format check/Input mask: Ensures that data entered follows a specified format.
Range check: Validates that the data falls within a defined range.
Step 3
What does the concept logical integrity of data refer to in general?
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Logical integrity of data refers to the correctness of data and ensuring that it is free of errors. It ensures that the data represents what it is supposed to and maintains its validity within the database.
Step 4
Explain how SQL injection can be used in a poorly designed DBMS to gain unauthorised access to data.
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SQL injection is a code injection technique that exploits vulnerabilities in a DBMS by inserting malicious SQL statements into a query via input fields. This can lead to unauthorized access to data, allowing attackers to manipulate or retrieve sensitive information.
Step 5
What is record locking in the context of a DBMS?
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Record locking occurs when a record is open for editing. During this time, the record is flagged as being in use, meaning other users are restricted from making changes to that specific record until it is unlocked.
Step 6
Explain what a distributed database system is.
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A distributed database system is one where parts of a database are spread across multiple locations or servers, allowing for improved data management and access efficiency as data is distributed across separate locations.
Step 7
State TWO situations where a single-server database will not be able to operate efficiently and the use of a distributed database becomes necessary.
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When the number of connected users becomes too large for a single server to handle efficiently.
When a business has operations spread over a large geographical area, making it necessary to use a distributed system.
Step 8
Differentiate between the Number and AutoNumber data types.
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Number: A numeric value entered by the user, which allows for any numerical input.
AutoNumber: A numeric value generated automatically by the database management system, typically used for unique identifiers in sequence.
Step 9
The data type of one of the fields shown in the diagram above is not suitable for its purpose. Provide a more suitable alternative data type.
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A suitable alternative for the ContactNumber field is a 'Text' data type, as it allows for the inclusion of leading zeros, country codes, and formatting characters like dashes.
Step 10
Give ONE reason why it is good practice to limit the length of a text field.
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Limiting the length of a text field helps save memory space and ensures that only valid data is captured, preventing extra or unnecessary information from being entered.
Step 11
Explain the term normalisation.
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Normalisation is the process of organizing data in a database to reduce data redundancy and improve data integrity. This involves creating separate tables for different data entities and establishing relationships between them using primary and foreign keys.
Step 12
State the type of relationship that exists between the ClientID fields in the tblClients table and the tblBookings table.
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The relationship between the ClientID fields in the tblClients table and the tblBookings table is a one-to-many relationship, as one client can have multiple bookings.
Step 13
Explain how the rule related to referential integrity has been violated.
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The rule related to referential integrity is violated when a record in the parent table (tblClients) cannot be deleted because there are existing records in the child table (tblBookings) that reference it. This creates a situation where data integrity is at risk.
Step 14
What needs to be done before the record can be deleted successfully from the tblClients table?
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Before the record can be deleted, all bookings associated with that client in the tblBookings table must be deleted or adjusted to ensure there are no orphan records.
Step 15
What is this type of key called?
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This type of key, which is formed from a combination of multiple fields to create a unique identifier, is called a composite key.
