MySQL选择从同一表中计数不同数据的最佳方法

Question

我试图获取相同表中但不同的where子句中的值计数。 哪一种是最好的方法

SELECT * FROM 
  (SELECT COUNT(id) FROM table WHERE post_id = 123 AND action_type IN(1,3,7,9,10)) as 'a',
  (SELECT COUNT(id) FROM table WHERE post_id = 123 AND action_type IN(2,7,8,18)) as 'b'

要么

SELECT COUNT(id) FROM table WHERE post_id = 123 AND action_type IN(1,3,7,9,10)
SELECT COUNT(id) FROM table WHERE post_id = 123 AND action_type IN(2,7,8,18)

注意：表包含数百万个值

Answer 1

您可以使用条件聚合，以便在一个查询中获得数据而无需子查询：

SELECT COUNT(CASE WHEN action_type IN(1,3,7,9,10) THEN id END) AS count_1,
       COUNT(CASE WHEN action_type IN(2,7,8,18) THEN id END) AS count_2
FROM table 
WHERE id = 123 

Answer 2

第一个，因为它将只执行一次并且优化了方式