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1CREATE TABLE IF NOT EXISTS `continents_currencies` AS SELECT `c`.`continent_code`,
2    `c`.`currency_code`,
3    COUNT(`c`.`currency_code`) AS `currency_usage` FROM
4    `countries` AS `c`
5GROUP BY `c`.`continent_code`,`c`.`currency_code`
6HAVING `currency_usage` > 1
7ORDER BY `c`.`continent_code` , `c`.`currency_code`;
8
9SELECT 
10    `cc`.*
11FROM
12    `continents_currencies` AS `cc`
13        LEFT JOIN
14    `continents_currencies` AS `cc2` ON `cc`.`continent_code` = `cc2`.`continent_code`
15        AND `cc`.`currency_usage` < `cc2`.`currency_usage`
16WHERE
17    `cc2`.`currency_usage` IS NULL;
18    
19DROP TABLE `continents_currencies`;