用於COUNT命令在MYSQL中創建查詢

Question

下面顯示了我的原始MY SQL表。

SELECT name, COUNT(city) AS "count_no" 
FROM emp 
GROUP BY name 
ORDER BY count_no DESC; 

我需要下面的結果。

SAM有4條。但倫敦有兩個城市的記錄。 我需要SAM的記錄有多少個城市。 我做了很多的查詢，但我無法創建我的SQL查詢。

Answer 1

添加DISTINCT以計數參數：

SELECT name, COUNT(DISTINCT city) AS "count_no" 
FROM emp 
GROUP BY name 
ORDER BY count_no DESC; 

Answer 2

SELECT name, COUNT(DISTINCT city) AS "count_no" 
FROM emp 
GROUP BY name 
ORDER BY count_no DESC;