ARRAY_MAP

A few SQL dialects, including ClickHouse, DuckDB, and Trino have introduced higher order functions with a lambda syntax to help implement features like this one. jOOQ can map a Java lambda to a SQL lambda, and emulate the feature using standard SQL functionality (using UNNEST and ARRAY_AGG) if the function isn't available.

SELECT array_map(ARRAY[1, 2, 2, 3], e -> square(e))

create.select(arrayMap(array(1, 2, 2, 3), DSL::square)).fetch();

+----------------+
| array_map      |
+----------------+
| [ 1, 4, 4, 9 ] |
+----------------+

arrayMap(array(1, 2, 2, 3), DSL::square)

(
  SELECT coalesce(
    array_agg((e * e)),
    CAST(ARRAY[] AS int[])
  )
  FROM UNNEST(ARRAY[1, 2, 2, 3]) t (e)
)

(
  SELECT coalesce(
    array_agg((e * e)),
    CAST(ARRAY[] AS array<int64>)
  )
  FROM (
    SELECT null e
    FROM UNNEST([STRUCT(1 AS dual)]) AS dual
    WHERE FALSE
    UNION ALL
    SELECT *
    FROM UNNEST(ARRAY[1, 2, 2, 3]) t
  ) t
)

arrayMap(
  e -> (e * e),
  ARRAY(1, 2, 2, 3)
)

(
  SELECT coalesce(
    array_agg((e * e)),
    CAST(ARRAY[] AS int4[])
  )
  FROM UNNEST(ARRAY[1, 2, 2, 3]) t (e)
)

transform(
  ARRAY(1, 2, 2, 3),
  e -> (e * e)
)

array_transform(
  ARRAY[1, 2, 2, 3],
  e -> (e * e)
)

(
  SELECT coalesce(
    array_agg((e * e)),
    CAST(ARRAY[] AS int array)
  )
  FROM UNNEST(ARRAY[1, 2, 2, 3]) t (e)
)

transform(
  ARRAY[1, 2, 2, 3],
  e -> (e * e)
)

/* UNSUPPORTED */

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