MySQL查詢分組和計數結果

Question

這是我當前的查詢-它顯示城市和距離值：

SELECT city, ( 6371 * acos( cos( radians(51.228482) ) * cos( radians( geo_breit
 ) ) * cos( radians( geo_lang ) - radians(6.772457) ) + sin( radians(51.228482) ) * sin( radians( geo_breit
 ) ) ) )
   AS distance
   FROM partner HAVING distance < 50 
   ORDER BY city

輸出：

我完全無法分組數據，因此它將返回以下內容

city                    total         max_distance
-------------------------------------------------------------
Bedburg                 2             29.445788818447983
Bergheim                2             32.83341311371813
Bergisch Gladbach       4             39.62206615477636
Bochum                  1             43.15766028349356
...

編輯：我添加了實際的查詢，問題是使用HAVING關鍵字時，分組/最大值不起作用..任何想法嗎？

Answer 1

您可以使用如下嵌套查詢：

SELECT cities.city,
       count(*) as total,
       max(cities.distance) as max_distance
FROM (SELECT city,
            ( 6371 * acos( cos( radians(51.228482) ) * cos( radians( geo_breit ) ) * cos( radians( geo_lang ) - radians(6.772457) ) + sin( radians(51.228482) ) * sin( radians( geo_breit) ) ) ) AS distance
       FROM partner HAVING distance < 50 
       ORDER BY city) as cities
  GROUP BY cities.city

或者您可以嘗試使用where子句代替

    SELECT city, count(*),
            max( 6371 * acos( cos( radians(51.228482) ) * cos( radians( geo_breit ) ) * cos( radians( geo_lang ) - radians(6.772457) ) + sin( radians(51.228482) ) * sin( radians( geo_breit) ) ) ) AS max_distance
       FROM partner 
       WHERE (6371 * acos( cos( radians(51.228482) ) * cos( radians( geo_breit ) ) * cos( radians( geo_lang ) - radians(6.772457) ) + sin( radians(51.228482) ) * sin( radians( geo_breit) ) ) < 50 
       ORDER BY city
       GROUP BY city

Answer 2

SELECT city, COUNT(city) as total, MAX(distance) AS max_distance
FROM table
GROUP BY city

Answer 3

您可以使用COUNT函數對出現的次數進行計數，並使用MAX函數通過GROUP BY查找最大距離值

詢問

select city, count(city) as total, max(distance) as max_distance
from your_table_name
group by city;

Answer 4

使用GROUP BY

SELECT city, COUNT(city) total, MAX(distance) max_distance
FROM table
GROUP BY city

GROUP BY語句與聚合函數結合使用，以按一個或多個列對結果集進行分組。