MySQL选择从同一表中计数不同数据的最佳方法

Question

i am trying to get count of values in same table but different where clause. Which one is best approach for that

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'

OR

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)

Note: Table contains millions of values

Answer 1

You can use conditional aggregation so as to get data in one query without subqueries:

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