-- Q1 returns (name,dod)
SELECT person_b.name, person.dod
FROM person JOIN person AS person_b
ON person.name = person_b.mother
AND person.dod IS NOT NULL
;

-- Q2 returns (name)
SELECT name
FROM person
WHERE gender = 'M'
EXCEPT
SELECT father
FROM person
ORDER BY name
;

-- Q3 returns (name)
SELECT mother AS name
FROM person
GROUP BY mother
HAVING COUNT(DISTINCT gender) = (SELECT COUNT(DISTINCT gender)
       		      	      	 FROM person)
AND mother IS NOT NULL
;

-- Q4 returns (name,father,mother)
SELECT person.name, person.father, person.mother
FROM person
WHERE person.dob <= ALL (SELECT person_b.dob
                         FROM person AS person_b
                         WHERE person.mother = person_b.mother
                         AND father = person_b.father)
AND person.father IS NOT NULL
AND person.mother IS NOT NULL
ORDER BY person.name
;

-- Q5 returns (name,popularity)
SELECT p.name, COUNT(p.name) AS popularity
FROM (SELECT SUBSTRING(name FROM '^[a-zA-Z]+') AS name
      FROM person) AS p
GROUP BY p.name
HAVING COUNT(p.name) > 1
ORDER BY popularity DESC, p.name
;

-- Q6 returns (name,forties,fifties,sixties)
SELECT father AS name,
       COUNT(CASE WHEN dob >= '19400101' AND dob < '19500101'
                  THEN name ELSE NULL END) AS forties,
       COUNT(CASE WHEN dob >= '19500101' AND dob < '19600101'
                  THEN name ELSE NULL END) AS fifties,
       COUNT(CASE WHEN dob >= '19600101' AND dob < '19700101'
                  THEN name ELSE NULL END) AS sixties
FROM person
GROUP BY father
HAVING COUNT(father) >= 2
UNION
SELECT mother AS name,
       COUNT(CASE WHEN dob >= '19400101' AND dob < '19500101'
                  THEN name ELSE NULL END) AS forties,
       COUNT(CASE WHEN dob >= '19500101' AND dob < '19600101'
                  THEN name ELSE NULL END) AS fifties,
       COUNT(CASE WHEN dob >= '19600101' AND dob < '19700101'
                  THEN name ELSE NULL END) AS sixties
FROM person
GROUP BY mother
HAVING COUNT(mother) >= 2
ORDER BY name
;


-- Q7 returns (father,mother,child,born)
SELECT father, mother, name AS child,
       RANK() OVER (PARTITION BY father ORDER BY dob) as born
FROM person
WHERE father IS NOT NULL
AND mother IS NOT NULL
ORDER BY father, mother, born
;

-- Q8 returns (father,mother,male)
SELECT father, mother,
       ROUND(100 * COUNT(CASE WHEN gender = 'M' THEN name ELSE NULL END) / COUNT(name), 0) as male
FROM person
GROUP BY father, mother
HAVING father IS NOT NULL
AND mother IS NOT NULL
ORDER BY father, mother
;