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What is CASE WHEN logic in SQL used for?

Parthiban Kannan
Updated on February 9, 2026

< 1 min read

  • CASE WHEN in SQL is used to create conditional logic in queries.
  • It evaluates conditions and returns different values based on the result.
  • In my project, we classified orders as “High Value” if Amount > 50,000, else “Normal”.
  • We also mapped status codes: CASE WHEN Status = ‘C’ THEN ‘Completed’ ELSE ‘Pending’.
  • It can be used in SELECT, WHERE, or ORDER BY clauses.
  • Reduces need for post-processing in Power Query.
  • Helps create business-friendly categories directly in the source.
  • Simplifies derived fields and conditional transformations.
  • Improves query efficiency by handling logic at extraction stage.
  • So CASE WHEN converts raw data into meaningful business context
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