Table: Student

Table: Enrollment

Task:

1. What is key attribute in Student? Why?

2. Define the entity integrity and explained.

3. Identify the null example, explained.

4. Explain by providing example for referential integrity.

5. Define Super key.

6. Define Primary key.

7. Define foreign key.

8. Define alternate key.

Task:
Display all information from the STUDENT table.

answer:

SELECT * FROM STUDENT;

Task:
Show only course code and title from the COURSE table.

Sql:

SELECT CourseCode, Title

FROM COURSE;

Task:
Display lecturer name as “Lecturer” and department as “Dept”.

SQL:

SELECT LecName AS Lecturer, Department AS Dept

FROM LECTURER;

Task:
List product ID, price, quantity, and total value (Price × Quantity) as TotalValue.

Answer (SQL):

Task:
Display a list of unique CourseCode values.

Answer (SQL):

SELECT DISTINCT CourseCode FROM ENROLLMENT;

Task:
List products priced above 100.

Answer (SQL):

SELECT * FROM PRODUCT WHERE Price > 100;

Task:
Display employees who work in IT and earn more than 2500.

Answer (SQL):

Task:
List customers ordered alphabetically by Name.

Answer (SQL):

SELECT * FROM CUSTOMER

ORDER BY Name ;

Task:
Find total sales amount by region.

Answer (SQL):

SELECT Region, SUM(Amount) AS TotalSales

FROM SALES

GROUP BY Region;

Task:
Show regions where total sales are greater than 600.

Answer (SQL):

Task:

List customer names with their corresponding order totals.

Answer (SQL):

SELECT customer.Name, `order`.Total

FROM customer

INNER JOIN `order`

ON customer.CustID = `order`.CustID;

Task:
Show all students and their enrolled course, if any.

Answer (SQL):

Task:
List employees earning more than the average salary.

Answer (SQL):

Task:
Combine both lists into one list of all unique employee names.

Answer (SQL):

Task:
Find all students whose names start with “Ami”.

Answer (SQL):

SELECT * FROM student

WHERE Name LIKE 'Ami%';

Task:
Display orders where the amount is between 300 and 700.

Answer (SQL): SELECT *

FROM ORDER

WHERE Amount BETWEEN 300 AND 700;

SELECT *

FROM ORDER

WHERE Amount >= 300 AND Amount <= 700;

Task:
Find customers with missing phone numbers.

Answer (SQL):

SELECT * FROM Customer WHERE Phone IS NULL

Task:
Count how many students are enrolled in each course.

Answer (SQL): SELECT COUNT(*) AS total_student

FROM ENROLLMENT;

INSERT INTO Staff VALUES ('S004', 'Aiman', 'B999'); -- ERROR

Reason: Branch B999 doesn’t exist in the Branch table.

FOREIGN KEY (branchNo)

REFERENCES Branch(branchNo)

ON DELETE CASCADE

ON UPDATE CASCADE;

If a branch is deleted or its branchNo is changed,
→ all related staff records will also be deleted or updated automatically.

Example:

DELETE FROM Branch WHERE branchNo = 'B001';

Result:

• B001 deleted from Branch.

• All staff working under B001 (Ali, Fatimah) are also deleted from Staff.

  
  

FOREIGN KEY (branchNo)

REFERENCES Branch(branchNo)

ON DELETE SET NULL

ON UPDATE SET NULL;

If a branch is deleted or updated,
→ the branchNo in the Staff table becomes NULL.

DELETE FROM Branch WHERE branchNo = 'B001';

FOREIGN KEY (branchNo)

REFERENCES Branch(branchNo)

ON DELETE SET DEFAULT;

FOREIGN KEY (branchNo)

REFERENCES Branch(branchNo)

ON DELETE NO ACTION;

• You cannot delete a branch if staff are still linked to it.

• The database will reject the delete.

Example:

DELETE FROM Branch WHERE branchNo = 'B001';

ERROR: Cannot delete Branch ‘B001’ because Staff records still reference it.

Task for students
• Identify entities
• Identify relationships
• Identify primary keys
• Draw ERD

Task for students
• Identify main entities
• Identify M:N relationship and associative table

Students only need to follow clear steps to reach better table designs. Start with First Normal Form. Move up when the structure holds.

Key points:

• Normalization improves consistency.

• Each table stores one subject.

• Each column stores a single value.

• Each table should rely on a primary key.

• Higher normal forms remove partial and transitive dependencies.

Issues:

1. Repeating groups like Course1, Course2, Course3.

2. Mixed subjects in one table.

3. Hard to update lecturers.

Follow these steps.

• Identify your system topic.
  Examples: booking, inventory, food ordering, student activity, clinic record.

• Select one process in your system that stores repeated details.
  Examples: one customer with multiple orders, one patient with multiple visits, one booking with multiple services.

• Build one unnormalized table. Include:
  – One main entity such as Customer, Patient, Student, User.
  – At least three repeating attributes such as Item1, Item2, Item3 or Service1, Service2, Service3.
  – At least two attributes linked to each repeated item such as Price1, Price2, Price3 or Quantity1, Quantity2, Quantity3.

• Include a minimum of five sample rows of data.

• Prepare the table in Excel.
  Columns must show the repeated groups clearly.

• Submit the table in your Google Drive folder and bring it to class for normalization steps.

  https://forms.gle/Zwva4hPedpBrTmk1A