將COUNT和DISTINCT關鍵字一起使用來計算不同的值

Question

我正在編寫查詢來計算數據庫表中不同值的數量。所以我寫了查詢爲：

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

我收到錯誤

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

誰能解釋我缺少什麼？

Answer 1

刪除count與左括號之間的空格。

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