🧪 SQL Practice: Combine and Compare Data

🧪 SQL Practice: Combine and Compare Queries

Use SQL set operators like UNION, INTERSECT, and MINUS to merge and compare data from different sources.

📋 Sample Tables

sales_team

name	region
Arif	Dhaka
Rafi	Chattogram
Nasrin	Dhaka

marketing_team

name	region
Nasrin	Dhaka
Ritu	Khulna
Faruk	Chattogram

🧠 Practice 1: Combine All Unique Employees

Goal: Show all distinct employee names from both teams.

SELECT name FROM sales_team
UNION
SELECT name FROM marketing_team;

Output:

name
Arif
Faruk
Nasrin
Rafi
Ritu

🧠 Practice 2: Find Common Employees

Goal: Find employees who work in both teams.

SELECT name FROM sales_team
INTERSECT
SELECT name FROM marketing_team;

Output:

name
Nasrin

🧠 Practice 3: Find Sales-Only Members

Goal: Show employees in sales team but not in marketing.

SELECT name FROM sales_team
MINUS
SELECT name FROM marketing_team;

Output:

name
Arif
Rafi

🧠 Practice 4: Combine with Duplicates (UNION ALL)

Goal: Combine names from both teams including duplicates.

SELECT name FROM sales_team
UNION ALL
SELECT name FROM marketing_team;

Output: Includes "Nasrin" twice since she’s in both.

name
Arif
Rafi
Nasrin
Nasrin
Ritu
Faruk

📌 Practice Tips:

• Try changing regions or adding new employees and rerun the queries.
• Try using ORDER BY after UNION for sorting.
• Use UNION ALL to keep duplicates if needed.

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