MySQL選擇從同一表中計數不同數據的最佳方法

Question

我試圖獲取相同表中但不同的where子句中的值計數。 哪一種是最好的方法

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：表包含數百萬個值

Answer 1

您可以使用條件聚合，以便在一個查詢中獲得數據而無需子查詢：

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

第一個，因為它將只執行一次並且優化了方式