🔁 SQL UNION, INTERSECT, MINUS Explained

🔁 SQL Set Operators: UNION, INTERSECT, MINUS

Set operators combine the results of two or more SELECT queries. Let's see how UNION, INTERSECT, and MINUS work using Bangladeshi employee examples.

📋 Sample Tables

sales_team

name	department
Arif	Sales
Rafi	Sales
Nasrin	Sales

marketing_team

name	department
Nasrin	Marketing
Ritu	Marketing
Faruk	Marketing

1️⃣ UNION

Goal: Combine all unique employee names from both teams.

SELECT name FROM sales_team
UNION
SELECT name FROM marketing_team;

Output:

name
Arif
Faruk
Nasrin
Rafi
Ritu

2️⃣ INTERSECT

Goal: Find names common in both teams (same name must exist in both queries).

SELECT name FROM sales_team
INTERSECT
SELECT name FROM marketing_team;

Output:

name
Nasrin

3️⃣ MINUS (or EXCEPT)

Goal: Find employees who are in sales_team but not in marketing_team.

SELECT name FROM sales_team
MINUS
SELECT name FROM marketing_team;

Output:

name
Arif
Rafi

📌 Summary:

• UNION: Combines unique rows from both queries.
• INTERSECT: Returns only common rows in both queries.
• MINUS: Returns rows in first query that are not in the second.
• ⚠ Note: Some databases use EXCEPT instead of MINUS.

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