Solution:Step 1: Understand UNION behaviorUNION combines all unique rows from both tables without duplicates.Step 2: Combine and remove duplicatesEmployees_A has 1,2,3 and Employees_B has 3,4,5. Combined unique set is 1,2,3,4,5.Final Answer:{1, 2, 3, 4, 5} -> Option AQuick Check:UNION result = all u

[Solved] Given two tables:Employees_A: {1, 2, 3}Employees_B: {3, 4, 5}What will be the result of SELECT id FROM Employees_A UNION SELECT id FROM Employees_B;? | SQL

SQL - Set Operations

Given two tables:
Employees_A: {1, 2, 3}
Employees_B: {3, 4, 5}
What will be the result of SELECT id FROM Employees_A UNION SELECT id FROM Employees_B;?

A{1, 2, 3, 4, 5}

B{3}

C{1, 2, 3}

D{3, 4, 5}

Step-by-Step Solution

Solution:

Step 1: Understand UNION behavior
UNION combines all unique rows from both tables without duplicates.
Step 2: Combine and remove duplicates
Employees_A has 1,2,3 and Employees_B has 3,4,5. Combined unique set is 1,2,3,4,5.
Final Answer:
{1, 2, 3, 4, 5} -> Option A
Quick Check:
UNION result = all unique rows combined [OK]

Quick Trick: UNION merges unique rows from both queries [OK]

Common Mistakes:

MISTAKES

Expecting duplicates in UNION result
Confusing UNION with INTERSECT
Ignoring unique row behavior

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Given two tables:

Step 1: Understand UNION behavior

Step 2: Combine and remove duplicates

Final Answer:

Quick Check:

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