4.1 Explain what a relational database is - NSC Information Technology - Question 4 - 2018 - Paper 2

Record locking is essential to prevent changes from being lost when multiple users are accessing the same data. If a record is locked, it ensures that only one user can make changes to it at a time, thereby avoiding conflicts and ensuring data integrity.

1. Setup user accounts and permissions to control access to the database.
2. Monitor database performance to ensure efficient operation and identify any issues that may arise.

In this context, a primary key is a unique identifier for each record in the tblStudents table. It ensures that each student can be individually identified and prevents duplicate entries in the database.

The StudentNumber field in the tblBooksBorrowed table is referred to as a foreign key. It creates a link to the primary key in the tblStudents table, establishing a relationship between the two tables.

A composite primary key is a combination of two or more fields in a table that, together, uniquely identify a record. This means that no single field alone can ensure uniqueness, but the combination does.

The relationship between the tblStudents and tblBooksBorrowed tables is a one-to-many relationship. This means that one student can borrow multiple books, while each book record in tblBooksBorrowed is associated with only one student.

Referential integrity was enforced to ensure that any StudentNumber in the tblBooksBorrowed table corresponds to an existing StudentNumber in the tblStudents table. This prevents orphaned records and maintains the accuracy and consistency of the data.

SELECT StudentName, StudentSurname, FundsAvailable
FROM tblStudents
WHERE FundsAvailable <= 30;

SELECT tblStudents.StudentNumber, COUNT(ISBN) AS NumberBorrowed
FROM tblStudents, tblBooksBorrowed
WHERE tblStudents.StudentNumber = tblBooksBorrowed.StudentNumber
GROUP BY tblStudents.StudentNumber
HAVING NumberBorrowed > 2;