Consulta SQL para GROUP BY, retorna grupos que correspondem às condições de LEAST, COALESCE

Primeiro, obtenha o tour_id s que correspondem às condições:

SELECT Tour_ID
FROM myTable 
WHERE organisation LIKE 'Ikea'
GROUP BY Tour_ID
HAVING LEAST(COALESCE(MIN(A), '2019-01-01'), COALESCE(MIN(B), '2019-01-01'), COALESCE(MIN(C), '2019-01-01'), COALESCE(MIN(D), '2019-01-01')) >= '2018-05-01' AND
       LEAST(COALESCE(MIN(A), '2019-01-01'), COALESCE(MIN(B), '2019-01-01'), COALESCE(MIN(C), '2019-01-01'), COALESCE(MIN(D), '2019-01-01')) < '2018-06-01';

Em seguida, coloque isso em uma consulta para obter as linhas originais. Aqui está uma maneira:

select t.*
from mytable t join
     (SELECT organisation, Tour_ID
      FROM myTable 
      WHERE organisation LIKE 'Ikea'
      GROUP BY organisation, Tour_ID
      HAVING LEAST(COALESCE(MIN(A), '2019-01-01'), COALESCE(MIN(B), '2019-01-01'), COALESCE(MIN(C), '2019-01-01'), COALESCE(MIN(D), '2019-01-01')) >= '2018-05-01' AND
             LEAST(COALESCE(MIN(A), '2019-01-01'), COALESCE(MIN(B), '2019-01-01'), COALESCE(MIN(C), '2019-01-01'), COALESCE(MIN(D), '2019-01-01')) < '2018-06-01'
     ) tt
     ON tt.tour_id = t.tour_id AND
        tt.organisation = t.organisation;