/* Select all rows from left table which aren't in right table.

   SELECT  l.*
   FROM    t_left l
   LEFT JOIN t_right r
   ON      r.value = l.value
   WHERE   r.value IS NULL
 */

/*
   TODO Add another layer of JOINs to show the value where name='Received' for
   the missing hashes.  Maybe we can parse dates from there.
 */
SELECT
    h.hash,
    h.name,
    substring(h.value, 0, 40)
FROM
    header h
INNER JOIN (
    SELECT
        l.hash
    FROM
        original l
    LEFT JOIN (
        SELECT
            hash
        FROM
            search_header
        WHERE
            name = 'Date'
        ) r
    ON
        r.hash = l.hash
    WHERE
        r.hash IS NULL
    ) missing
ON
    missing.hash = h.hash
WHERE
    -- name IN ('Subject', 'Received', 'Date')
    name IN ('From', 'Subject')
ORDER BY
    h.value
;