v.24.4Improvement

Make transform Function Return First Match

Official CH changelog text
Make transform always return the first match. #62518 (Raúl Marín).
transform function now returns the first matching value consistently.

Why it matters

This update ensures that the transform function in ClickHouse always returns the value corresponding to the first matching key, improving predictability and correctness when multiple keys match. This avoids ambiguous or unexpected results in data transformations.

How to use it

Use the transform function as usual in your queries. With this change, it will consistently return the value of the first key matched in the provided mappings without requiring any additional configuration.

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