一起使用 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;

我遇到错误

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

谁能解释我错过了什么？

Answer 1

删除count 和左括号之间的空格。

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