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Why do we need set operations like UNION in SQL?

easy📝 Conceptual Q1 of 15
SQL - Set Operations
Why do we need set operations like UNION in SQL?
ATo update values in a table
BTo create new tables from scratch
CTo delete rows from a table
DTo combine results from multiple queries into one result set
Step-by-Step Solution
Solution:

  1. Step 1: Understand the purpose of set operations

    Set operations like UNION combine results from two or more SELECT queries into a single result set.

  2. Step 2: Compare with other SQL commands

    Commands like DELETE or UPDATE modify data, but do not combine query results.

  3. Final Answer:

    To combine results from multiple queries into one result set -> Option D

  4. Quick Check:

    Set operations purpose = Combine results [OK]
Quick Trick: Set operations combine query results, not modify data [OK]
Common Mistakes:
MISTAKES
  • Confusing set operations with data modification commands
  • Thinking UNION creates new tables
  • Assuming UNION deletes data

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