同时使用COUNT和DISTINCT关键字来计算不同的值

Question

我正在编写查询来计算数据库表中不同值的数量。所以我把查询写成：

select count ( distinct user_id ) as unique_users from 1_time_access;

我收到错误

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'distinct user_id ) as unique_users from 1_time_access' at line 1

任何人都可以解释我错过了什么吗？

Answer 1

删除count与左括号之间的空格。

select count(distinct user_id) as unique_users from 1_time_access;