The Internet café must keep records of the users and be able to charge users for the time that they were logged onto the Internet - NSC Information Technology - Question 4 - 2016 - Paper 2

One way to indicate the time format is to utilize combo boxes; one for hours and another for minutes. This would guide users to select the time without needing to type it out manually.

Valid data adheres to the predefined formats and constraints, such as entering hours in the range of 0 to 24 for the time. Correct data, however, means that the entered information aligns with the expected real-world values. For instance, even if '26' is entered as a time, it is technically valid due to format adherence but is incorrect because it exceeds the possible range of hours.

The tblComputers table should have its primary key, ComputerNumber, used as a foreign key in the tblUsers table. This linkage allows each computer in the tblComputers to be associated with multiple users in tblUsers.

The SQL query to accomplish this is:

SELECT LogoutTime
FROM tblUsers
WHERE PaymentMethod = 'Debit Card'
ORDER BY LogoutTime;

The SQL query for this update is:

UPDATE tblUsers
SET PaymentMethod = 'Credit Card'
WHERE UserIDNo = '73110117564076';

The SQL query to count the users who paid with cash is:

SELECT COUNT(UserIDNo) AS CountCashIds
FROM tblUsers
WHERE PaymentMethod = 'Cash';

The SQL query to extract these users is:

SELECT * FROM tblUsers
WHERE (LoginTime > '12:00') AND (LoginDate = '2016/02/25');

The audit trail captures information such as who made changes to the database, what changes were made, and when those changes occurred.

1. Collecting data through credit card transactions when purchases are made.
2. Tracking user behavior when they browse the Internet or select webpages.

This process is known as data mining.