Designing Database

Question 1

What is the purpose of the **FOREIGN KEY** constraint on DeptID in the Employees table?

A.

A) To ensure DeptID values are unique in Employees

B.

B) To link Employees to valid DeptID values in Departments

Explanation: **Foreign keys** enforce referential integrity by ensuring DeptID in Employees matches existing primary keys in Departments.

C.

C) To automatically delete employees when departments are removed

D.

D) To sort employees by department

Question 2

What data type is used for **Salary** in Employees, and why?

A.

A) INT, for whole numbers only

B.

B) VARCHAR(50), for text formatting

C.

C) DECIMAL(10,2), for precise monetary values

Explanation: **DECIMAL(10,2)** supports exact decimal precision needed for currency.

D.

D) DATE, for salary history

Question 3

In the companyDB schema, which table structure correctly implements a **many-to-many** relationship between employees and projects?

A.

A) Adding ProjectID to Employees table

B.

B) Adding EmpID to Projects table

C.

C) Creating EmployeeProjects with EmpID and ProjectID as composite primary key

Explanation: The **EmployeeProjects** table uses EmpID and ProjectID as a composite primary key with foreign keys to resolve the many-to-many relationship.

D.

D) Adding both EmpID and ProjectID to Departments

📝 Designing Database - CompanyDB

Quiz Complete!