Możesz użyć do tego zapytania w ten sposób
UPDATE table_a a
SET a.alcohol_spirits = a.alcohol_spirits +
(SELECT
count(table_b.itemId)
FROM table_b
WHERE headAlias = 'alcohol-spirits'
AND country IN('US,SE')
AND FIND_IN_SET(a.country, table_b.headdestinations)
)