Convert week number to Monday (ISO 8601)

pg-convert-week-number-to-monday-iso-8601.sql

WITH week AS (

  -- change week number and year as you need
  SELECT CAST(2 AS INTEGER) AS number,
    CAST(2022 AS INTEGER) AS year
),
first_date AS (
  SELECT CAST(year || '-01-01' AS DATE) AS d
  FROM week
),
first_monday AS (
  SELECT (d + (8 - CAST(EXTRACT(DOW FROM d) AS INTEGER)) % 7) AS d
  FROM first_date
)
SELECT first_monday.d + (week.number - 1) * 7
FROM week
  CROSS JOIN first_monday;