多個表（一個是子查詢）加入

Question

我有（再次）此表：

User: 
id | name 
------------- 
1 | 'John' 
2 | 'Peter' 
3 | 'Luke' 

Accounts: 
id | userid | amount | date 
-------------------------- 
1 | 1  | 1000 | '2012-01-26' 
2 | 1  | 2000 | '2011-12-25' 
3 | 1  | 1000 | '2012-01-25' 
4 | 2  | 1500 | '2012-01-15' 
5 | 3  | 2500 | '2011-11-30' 

我需要收集數據，所以我有，在同一時間，與用戶一個結果，計數每個用戶的帳戶金額總和，以及每個用戶的帳戶數量，但只有當前年份的日期...

這樣的事情：

Some-query: 
UserName | CountAccts | SumAccts | CountAcctsThisYear 
----------------------------------------------------- 
'John' | 3   | 4000  | 2 
'Peter' | 1   | 1500  | 1 
'Luke' | 1   | 2500  | 0 

I管理與此查詢，以獲得前3列：

SELECT u.name as Username, 
     COUNT(a.id) as CountAccts, 
     SUM(a.amount) as SumAccts 
FROM User u 
LEFT JOIN Accounts a ON u.id = a.userid 
GROUP BY u.id; 

另外，我可以拿到第一和最後一列與此另一個：

SELECT u.name as Username, 
     COUNT(acctsthisyear.id) as CountAcctsThisYear 
FROM User u 
LEFT JOIN (SELECT a.id 
      FROM Accounts a 
      WHERE DATE_FORMAT(a.date,'%Y') = DATE_FORMAT(CURDATE(),'%Y') 
     ) AS acctsthisyear ON u.id = acctsthisyear.userid 
GROUP BY u.id; 

但是，這裏的問題，我不能設法使用這兩個查詢以這種方式得到我期待的最終結果...

我有... - 試圖左用用戶表加入帳戶表和acctsthisyear子查詢（分組由us.id字段），但我得到的是這樣的：

UserName | CountAccts | SumAccts | CountAcctsThisYear 
----------------------------------------------------- 
'John' | 6   | 6000  | 6 
'Peter' | 1   | 1500  | 1 
'Luke' | 0   | 0  | 0 

（不記得所有的細節，但問題是，例如，2個結果「約翰」在CountAcctsThisyear，得到的結果過分重複，所有乘上... ）

• 試圖每個查詢作爲子查詢： SELECT * FROM （與u.id第一查詢作爲UFID還選擇）AS第一， （與u.id第二查詢作爲USID還選擇）AS第二 GROUP BY ufid，usid

，得到了這樣的事情：

UserName | CountAccts | SumAccts | CountAcctsThisYear 
----------------------------------------------------- 
'John' | 3   | 4000  | 2 
'Peter' | 1   | 1500  | 2 
'Luke' | 1   | 2500  | 2 
'John' | 3   | 4000  | 1 
'Peter' | 1   | 1500  | 1 
'Luke' | 1   | 2500  | 1 
'John' | 3   | 4000  | 0 
'Peter' | 1   | 1500  | 0 
'Luke' | 1   | 2500  | 0 

（如果我通過元素反轉集團，我得到的是相同的，但在不同的順序分組...）

任何方式...就是這樣......關於什麼是正確的方式來實現我所期待的任何想法？我與它很沮喪，因爲我真的在SQL方面的專家，特別是在連接： -/

Answer 1

試試這個：

SELECT u.`Name` as UserName, 
     Count(*) as CountAccts, 
     SUM(a.`amount`) as SumAccts, 
     COALESCE(iTable.CountAcctsThisYear, 0) as CountAcctsThisYear 
FROM `User` u INNER JOIN `Accounts` a 
        ON u.`ID` = a`.`ID` 
       LEFT JOIN 
        (SELECT `ID`, Count(*) as CountAcctsThisYear 
        FROM `Accounts` 
        WHERE DATE_FORMAT(`date`,'%Y') = DATE_FORMAT(CURDATE(),'%Y') 
        GROUP BY `ID`) as iTable 
       ON `User`.`ID` = iTable.`ID` 
GROUP BY `User`.`Name` 

Answer 2

SELECT u.name as Username, 
     COUNT(a.id) as CountAccts, 
     SUM(a.amount) as SumAccts 
FROM User u 
INNER JOIN Accounts a ON u.id = a.userid 
GROUP BY u.id,YEAR(a.date) 

一次嘗試這個！

Answer 3

SELECT u.name as Username, 
     COUNT(a.id) as CountAccts, 
     SUM(a.amount) as SumAccts, 
     SUM(CASE WHEN YEAR(a.date) = YEAR(CURDATE()) THEN 1 ELSE 0 END) 
      as CountAcctsThisYear 
FROM User u 
LEFT JOIN Accounts a ON u.id = a.userid 
GROUP BY u.id; 

Answer 4

SELECT u.name as Username, 
     COUNT(a.userid) as CountAccts, 
     SUM(a.amount) as SumAccts, 
     SUM(CASE WHEN YEAR(a.date) = YEAR(CURDATE()) THEN 1 ELSE 0 END) 
      as CountAcctsThisYear 
FROM Accounts a 
INNER JOIN User u ON u.id = a.userid 
GROUP BY a.userid;