MySQL 8.0

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CREATE TABLE `voting` (`participant` varchar(11) NOT NULL, `firstVote` varchar(11) NOT NULL, `secondVote` varchar(11) NOT NULL);
INSERT INTO `voting` (`participant`, `firstVote`, `secondVote`) VALUES
  ('Mary', 'Jane', 'Holland'),
  ('Jane', 'Mary', 'Holland'),
  ('Donatella', 'Mary', 'Jane'),
  ('Holland', 'Mary', 'Jane');

Records: 4  Duplicates: 0  Warnings: 0


SELECT v1.participant,
       COALESCE(
         SUM(
           2 * (v1.participant = v2.firstVote) + 
           (v1.participant = v2.secondVote)
         ), 
         0
       ) AS votesReceived
FROM voting v1 LEFT JOIN voting v2
ON v1.participant IN (v2.firstVote, v2.secondVote)
GROUP BY v1.participant
ORDER BY votesReceived DESC;


participant
votesReceived


Mary
6

Jane
4

Holland
2

Donatella
0


SELECT v1.participant,
       SUM(
         CASE v1.participant  
           WHEN v2.firstVote THEN 2
           WHEN v2.secondVote THEN 1
           ELSE 0
         END
       ) AS votesReceived
FROM voting v1 LEFT JOIN voting v2
ON v1.participant IN (v2.firstVote, v2.secondVote)
GROUP BY v1.participant
ORDER BY votesReceived DESC;


participant
votesReceived


Mary
6

Jane
4

Holland
2

Donatella
0