DECLARE
  dates STRING;
SET
  dates = (
  SELECT
    CONCAT('("', STRING_AGG(DISTINCT REPLACE(LEFT(started_at,10),"-",""), '", "'), '")'),
  FROM
    `analytics-dev-308300.dtm_engagement.ft_content_consumption` );

EXECUTE IMMEDIATE
  FORMAT("""
SELECT DISTINCT * FROM
    (SELECT
    user_id,
    group_id,
    REPLACE(LEFT(started_at,10),"-","") as started_at,
    FROM
    `analytics-dev-308300.dtm_engagement.ft_content_consumption`)
PIVOT
(COUNT(*) as s
for started_at in %s)""",dates)