BigQuery の Standard SQL で Legacy SQL の FLATTEN(table_name) 相当の処理を行う SQL

alt_flattern.sql

  WITH t AS (
SELECT *
  FROM UNNEST(ARRAY<STRUCT<id INT64, `names` ARRAY<STRING>>>
              [(1, ['A', 'B']), (2, ['A']), (3, ['A'])]))

SELECT t.id
     , `name`
  FROM t
  JOIN UNNEST(t.`names`) AS `name`
ORDER BY 1, 2

result.md

Row	id	name
1	1	A
2	1	B
3	2	A
4	3	A