計數總數和細分

我想知道有多少用戶來自該城市內的城市和自治市鎮/鄰里。所以我正在尋找一個將輸出這兩個計數結果的查詢。我有一張帶有用戶數據的表格，沒有特定的城市和自治市鎮/社區，但是有來自每個用戶的郵政編碼。這可以用來匹配表格郵編，女巫包含城市和鄰里數據。計數總數和細分

表用戶

+----+--------------------+--------------+ 
| ID | User    | Postcode  | 
+----+--------------------+--------------+ 
| 10 | John Doe   | 1100—99-AB | 
| 11 | Shara Lee   | 1201—34-CD | 
| 12 | Patrick Star  | 1100—99-AB | 
| 13 | Oswald Harvey  | 1100—99-AB | 
| 14 | Samuel Jackson  | 1401—34-TR | 
| 15 | Richard Lionheart | 1744—39-AA | 
| 16 | Shamanta Jones  | 2334—95-AC | 
| 17 | James Rooney  | 1401—34-TR | 
| 18 | Chandler Bing  | 3334—23-AA | 
| 19 | Jessica Burner  | 2277—99-RA | 
+----+--------------------+--------------+

表郵政編碼

+------------+--------------+-------------+ 
| Postcode | City   | Borough  | 
+------------+--------------+-------------+ 
| 1100—99-AB | New York  | Manhattan | 
| 1201—34-CD | New York  | Manhattan | 
| 1401—34-TR | New York  | Bronx  | 
| 1744—39-AA | New York  | Harlem  | 
| 2334—95-AC | Newark  |    | 
| 6334—95-AC | Detroit  | Greektown | 
| 3334—23-AA | Philadelphia | Penn Center | 
| 2277—99-RA | Newark  |    | 
+------------+--------------+-------------+

結果我之後

+--------------+--------------+-------------+---------------+ 
| City   | Total_City | Borough  | Total_Borough | 
+--------------+--------------+-------------+---------------+ 
| New York  | 7   | Manhattan | 4    | 
| New York  | 7   | Bronx  | 2    | 
| New York  | 7   | Harlem  | 1    | 
| Newark  | 2   |    | 2    | 
| Philadelphia | 1   | Penn Center | 1    | 
+--------------+--------------+-------------+---------------+

這是多遠我跟我的查詢得到。這確實可以計算出自治區/鄰區的數量，但不幸的是，它並未顯示城市總數。

SELECT City, Borough, COUNT(City) AS Total_City, COUNT(Borough) AS Total_Borough, 
    FROM `users` u 
    LEFT JOIN `postcodes` p ON p.postcode = u.postcode 
GROUP BY City, Borough

見我的例子上http://rextester.com/DFRV4183

來源

2017-08-27 Kaspar

差不多，但請參閱[爲什麼我應該爲我認爲是非常簡單的SQL查詢提供一個MCVE]（http://meta.stackoverflow.com/questions/333952/why-should-i-provide- an-mcve-for-what-seems-to-very-simple-sql-query） – Strawberry

@Strawberry，你說得很對。我已經從Rextester添加了一個工作示例。 – Kaspar

這裏有一種方法......

SELECT a.*, b.total total_city 
    FROM 
    (SELECT p.city 
      , p.borough 
      , COUNT(*) total 
     FROM postcodes p 
     JOIN myusers u 
      ON u.postcode = p.postcode 
     GROUP 
      BY city 
      , borough 
    ) a 
    JOIN 
    (SELECT p.city 
      , COUNT(*) total 
     FROM postcodes p 
     JOIN myusers u 
     ON u.postcode = p.postcode 
    GROUP 
      BY city 
    ) b 
    ON b.city = a.city;

你也可以做這樣的事情，但我不相信，結果是更容易理解...

SELECT city 
    , borough 
    , COUNT(*) total 
    FROM postcodes p 
    JOIN myusers u 
    ON u.postcode = p.postcode 
GROUP 
    BY city 
    , borough WITH ROLLUP;

最後，你可以使用變量。也許我會在後面發表一個答案......如果有人不打我的話。

來源

2017-08-28 09:44:06 Strawberry

SELECT b.City, Borough, Total_City, Total_Borough from 
    (SELECT City, coalesce(COUNT(User),0) AS Total_City 
    FROM `Users` u 
    right JOIN `Postcodes` p ON p.postcode = u.postcode 
    GROUP BY City) as c 
inner join 
(
SELECT City, coalesce(Borough,'Undefined')as Borough,coalesce(COUNT(User),0) AS Total_Borough, p.postcode 
    FROM `users` u 
    right JOIN `postcodes` p ON p.postcode = u.postcode 
GROUP BY City, Borough 
) as b 
on b.City=c.City

來源

2017-08-27 16:49:09

外部查詢有什麼作用？ – Strawberry

Thnx，我想使用subquerys是要走的路。你的建議看起來很接近，但不幸的是它沒有列出所有的自治市鎮。 http://sqlfiddle.com/#!9/3e7c6e/12 – Kaspar

立即嘗試並告訴我。 –

計數總數和細分

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