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 principle stands for 'Garbage In, Garbage Out.' This means that if the data entered into the system is incorrect or of poor quality, the output produced will also be flawed or invalid.
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 the data entered adheres to a specific format, such as a phone number or email address.
Range check/Validation rules: Verifies that the data falls within a specified range or adheres to defined rules, such as age being between 0 and 120.
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 and accuracy of data within a database. It ensures that the data is free of errors and consistent across all contexts.
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 input fields. This can allow an attacker to manipulate the database, execute arbitrary SQL commands, and access or modify data without proper authorisation.
Step 5
What is record locking in the context of a DBMS?
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Record locking is a mechanism used to prevent multiple users from modifying the same record simultaneously. When a record is in use, it is flagged to indicate that no other user can make changes to it until it is released.
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 (servers) that work together. This architecture allows for better resource management, redundancy, and accessibility.
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: As user demand increases, a single server may struggle to process all requests efficiently.
When a business is spread over a large geographical area: A distributed database can provide local access to data for users in different locations, reducing latency.
Step 8
Differentiate between the Number and AutoNumber data types.
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The Number data type represents any numeric value entered by the user, while the AutoNumber data type generates a unique numeric value automatically by the system for each new record, ensuring that each entry is distinct.
Step 9
The data type of one of the fields shown in the diagram above is not suitable for its purpose.
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The ContactNumber field is defined as 'Number', which may not be suitable as phone numbers can contain leading zeros or special characters (e.g., '+', '-', '()') that are not represented in a numeric format. A better alternative would be to use the Text data type.
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 to save memory space by avoiding unnecessary or excessive data storage, ensuring that only relevant information is captured.
Step 11
Explain the term normalisation.
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Normalisation is the process of structuring a relational database in a way that reduces redundancy and improves data integrity by organizing data into tables and establishing relationships based on defined constraints.
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, where 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 of referential integrity has been violated because there are existing references in the tblBookings table that depend on the ClientID being deleted from the tblClients table. Since there are associated records in tblBookings, deleting the client would leave orphaned records.
Step 14
What needs to be done before the record can be deleted successfully from the tblClients table?
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Before deleting the ClientID from the tblClients table, all records in the tblBookings table that reference this ClientID must be deleted or updated to ensure that there are no relationships violating referential integrity.
Step 15
What is this type of key called?
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This type of key is called a composite key, which is a combination of two or more fields used to uniquely identify a record in a table.
