Selection operation in DBMS Theory - Mini Project: Build & Apply

Selection Operation in DBMS

📖 Scenario: You are working with a simple database table called Employees that stores information about employees in a company. You want to learn how to use the selection operation in SQL to find specific employees based on certain conditions.

🎯 Goal: Build an SQL query step-by-step that selects employees from the Employees table who meet a specific condition using the selection operation.

📋 What You'll Learn

Create a table named Employees with columns EmpID, Name, and Department.

Insert specific employee records into the Employees table.

Write a selection query to find employees in the Sales department.

Complete the query to select only the Name and Department columns.

💡 Why This Matters

🌍 Real World

Selection operations are used in databases to find specific records that meet certain criteria, such as finding all employees in a particular department.

💼 Career

Database administrators and developers use selection queries daily to retrieve meaningful data from large datasets efficiently.

1

Create the Employees table

Write an SQL statement to create a table called Employees with three columns: EmpID as an integer, Name as text, and Department as text.

DBMS Theory

-- Write the CREATE TABLE statement for Employees
-- Your code here

Need a hint?

Use CREATE TABLE Employees (EmpID INT, Name TEXT, Department TEXT); to create the table.

2

Insert employee records

Write SQL statements to insert these exact records into the Employees table: (1, 'Alice', 'Sales'), (2, 'Bob', 'HR'), (3, 'Charlie', 'Sales').

DBMS Theory

CREATE TABLE Employees (
  EmpID INT,
  Name TEXT,
  Department TEXT
);
-- Insert the three employee records below
-- Your code here

Need a hint?

Use INSERT INTO Employees (EmpID, Name, Department) VALUES (1, 'Alice', 'Sales'), (2, 'Bob', 'HR'), (3, 'Charlie', 'Sales');

3

Select employees from Sales department

Write an SQL SELECT statement to select all columns from Employees where the Department is exactly 'Sales'. Use WHERE Department = 'Sales'.

DBMS Theory

CREATE TABLE Employees (
  EmpID INT,
  Name TEXT,
  Department TEXT
);
INSERT INTO Employees (EmpID, Name, Department) VALUES
  (1, 'Alice', 'Sales'),
  (2, 'Bob', 'HR'),
  (3, 'Charlie', 'Sales');
-- Select all columns for employees in Sales department
-- Your code here

Need a hint?

Use SELECT * FROM Employees WHERE Department = 'Sales'; to get all Sales employees.

4

Select only Name and Department columns

Modify the previous SELECT statement to select only the Name and Department columns for employees in the Sales department.

DBMS Theory

CREATE TABLE Employees (
  EmpID INT,
  Name TEXT,
  Department TEXT
);
INSERT INTO Employees (EmpID, Name, Department) VALUES
  (1, 'Alice', 'Sales'),
  (2, 'Bob', 'HR'),
  (3, 'Charlie', 'Sales');
-- Select only Name and Department columns for Sales employees
-- Your code here

Need a hint?

Use SELECT Name, Department FROM Employees WHERE Department = 'Sales'; to get only those columns.