case when … (searched)

Case is a conditional SQL expression: It returns the value of that then expression which follows the first true when clause. If no when condition is true, the value of the else expression is returned or null if there is no else.

SELECT CASE WHEN x > 100 THEN 'too large'
                         ELSE 'ok'
             END
  FROM …

Related

• Tutorials

  • The Three-Valued Logic of SQL

  • case — Conditional Expressions

• Other conditional expressions

  • case … when … (simple)

  • coalesce(…, …[, …]*)

  • nullif(…, …)

  • case … when <op> … (extended)

  • case … when …, … (comma-separated)

• Product specific features: if, iif, decode.

Normative References

The searched case expression is defined in ISO/IEC 9075-2:2023 as mandatory feature F261-02.