PostgreSQL SQL SELECT CASE WHEN

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ThesqlCASEexpression is a generic conditional expression,similar to if/else statements in other programming languages:

  1. CASE WHEN condition THEN result
  2. [WHEN ...]
  3. [ELSE result]
  4. END

An example:

  1. SELECT * FROM test;
  2.  
  3. a
  4. ---
  5. 1
  6. 2
  7. 3
  8.  
  9.  
  10. SELECT a,CASE WHEN a=1 THEN 'one'
  11. WHEN a=2 THEN 'two'
  12. ELSE 'other'
  13. END
  14. FROM test;
  15.  
  16. a | case
  17. ---+-------
  18. 1 | one
  19. 2 | two
  20. 3 | other


http://www.postgresql.org/docs/current/static/functions-conditional.html

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