有沒有更好的方法來編寫這個特定的查詢？

Question

SELECT (res.phone_number_count + res.computer_count) AS user_count FROM (
    SELECT COUNT(DISTINCT phone_number_id) AS phone_number_count, COUNT(DISTINCT computer_id) AS computer_count 
    FROM opinions 
    WHERE case_id = 1 
) AS res; 

我想要計算唯一的phone_number_ids和computer_ids。

Answer 1

如何：

SELECT COUNT(DISTINCT phone_number_id) + COUNT(DISTINCT computer_id) AS user_count 
FROM opinions 
WHERE case_id = 1