mysql - 选择表中不同列的计数

Question

假设我有一个格式如下的 sql 表:

id INT PRIMARY KEY AUTO_INCREMENT,
action TINYINT NOT NULL,
user_id INT NOT NULL

我想构建一个产生与以下相同结果的查询:

SELECT
    (SELECT COUNT(*), action FROM table WHERE action=1 AND user_id=1),
    (SELECT COUNT(*), action FROM table WHERE action=2 AND user_id=1),
    (SELECT COUNT(*), action FROM table WHERE action=3 AND user_id=1),
    ...
    (SELECT COUNT(*), action FROM table WHERE action=n AND user_id=1)

(1<->n 只是action 的范围)

但没有所有的冗余和低效率。

Answer 1

如果我对问题的理解正确，这就是您要查找的内容:

SELECT   action, COUNT(*)
FROM     your_table
WHERE    user_id = 1
GROUP BY action