Question

嗨我正在扩展一个查询，我有以下问题，我有一个表3用户，他们与其他表连接（加入），现在在这些表中，用户可以或不可以拥有数据，这取决于他们动作。

SELECT 

COALESCE (credit.received, 0) AS CreditReceived, 
COALESCE (purchase.used, 0) AS CreditUsed, 
COALESCE (purchase.NumberOfPurchase, 0) AS NumberOfPurchase, 
COALESCE (credit.received, 0) - COALESCE (purchase.used, 0) AS UserCredit,

dbo.[User].id_user, 
dbo.[User].name, 
dbo.[User].town, 
dbo.[User].country

FROM (SELECT DISTINCT id_user
FROM dbo.UserCredit
UNION
SELECT DISTINCT id_user
FROM dbo.UserPurchase) AS users 

INNER JOIN
dbo.[User] ON users.id_user = dbo.[User].id_user 

LEFT OUTER JOIN
(SELECT        
id_user, 
SUM(creditRecieved) AS received
FROM            
dbo.UserCredit AS UserCredit_1
GROUP BY id_user) AS credit 
ON users.id_user = credit.id_user 

LEFT OUTER JOIN
(SELECT        
id_user, 
SUM(creditUsed) AS used,
COUNT(creditUsed) AS NumberOfPurchase
FROM            
dbo.UserPurchase AS UserPurchase_1
GROUP BY id_user) AS purchase 
ON users.id_user = purchase.id_user

信息来自这些表格;

表dbo.user

id_user     name        town           country
----------- ----------- -------------- -------------
1           George      New York       USA
2           Lucas       San Diego      GB
3           Steven      San Fran       Germany

表dbo.UserCredit

id          id_user     creditRecieved PurchasePrice
----------- ----------- -------------- -------------
1           1           150            750
2           1           25             100
3           2           65             15

表dbo.UserPurchase

id          id_user     creditUsed  date
----------- ----------- ----------- -----------
1           1           175         NULL
2           2           3           NULL
3           2           2           NULL

我得到的只是两个第一个user_id的结果，而第三个（史蒂文）没有显示在结果中，我想这是因为id不存在于另外两个表格，但我希望能用COALESCE修正，其中四个将设为0.我做错了什么？

Answer 1

您不需要派生表＆＃34;用户。＆＃34;它不包含所有用户ID，并且是不必要的。删除它并将连接保留在用户表中，它应该可以正常工作。

Answer 2

将第一个DISTINCT替换为dbo。[User]而不是dbo.UserCredit，它给了我正确的结果;由于COALESCE，概述中的所有用户都有信用或没有信用：）

SELECT 

COALESCE (credit.received, 0) AS CreditReceived, 
COALESCE (purchase.used, 0) AS CreditUsed, 
COALESCE (purchase.NumberOfPurchase, 0) AS NumberOfPurchase, 
COALESCE (credit.received, 0) - COALESCE (purchase.used, 0) AS UserCredit,

dbo.[User].id_user, 
dbo.[User].name, 
dbo.[User].town, 
dbo.[User].country

FROM (SELECT DISTINCT id_user
FROM dbo.[User]
UNION
SELECT DISTINCT id_user
FROM dbo.UserPurchase) AS users 

INNER JOIN
dbo.[User] ON users.id_user = dbo.[User].id_user 

LEFT OUTER JOIN
(SELECT        
id_user, 
SUM(creditRecieved) AS received
FROM            
dbo.UserCredit AS UserCredit_1
GROUP BY id_user) AS credit 
ON users.id_user = credit.id_user 

LEFT OUTER JOIN
(SELECT        
id_user, 
SUM(creditUsed) AS used,
COUNT(creditUsed) AS NumberOfPurchase
FROM            
dbo.UserPurchase AS UserPurchase_1
GROUP BY id_user) AS purchase 
ON users.id_user = purchase.id_user

T-SQL（Azure）仅显示2个结果而不是3个结果

2 个答案: