Available in versions: Dev (3.18)

This is experimental functionality, and as such subject to change. Use at your own risk!

This documentation is for the unreleased development version of jOOQ. Click on the above version links to get this documentation for a supported version of jOOQ.

Unreachable CASE clauses

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

When a searched CASE expression contains unreachable WHEN or ELSE clauses, we can remove them.

Using Settings.transformPatternsUnreachableCaseClauses, the following transformations can be achieved:

-- With Settings.transformPatternsUnreachableCaseClauses active, this:
SELECT
  CASE WHEN a = b THEN 1 WHEN TRUE THEN 2 WHEN c = d THEN 3 END,
  CASE WHEN a = b THEN 1 WHEN FALSE THEN 2 WHEN c = d THEN 3 END
FROM tab;

-- ... is transformed into the equivalent expression:
SELECT
  CASE WHEN a = b THEN 1 ELSE 2 END,
  CASE WHEN a = b THEN 1 WHEN c = d THEN 3 END
FROM tab;

A more subtle unreachable WHEN clause is a clause that has already been listed, irrespective of the THEN clause. While removing it is a correct transformation, the duplicate might be likely due to a typo.

-- With Settings.transformPatternsUnreachableCaseClauses active, this:
SELECT
  CASE 
    WHEN a = b THEN 1 
    WHEN c = d THEN 2 
    WHEN a = b THEN 3
  END
FROM tab;

-- ... is transformed into the equivalent expression:
SELECT
  CASE 
    WHEN a = b THEN 1 
    WHEN c = d THEN 2 
  END
FROM tab;

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