SQL INNER JOINing 2 子查询

Question

我正在尝试将这两个子查询（我认为这就是所谓的）内部连接在一起，其中第一个查询的 branchName 等于第二个查询的 branchName。

但是，他们似乎不想联合起来，而且由于我对 SQL 的了解有限，我似乎无法找到解决此问题的方法。我尝试在各种位置移动括号，但它也不喜欢那样。

SELECT * 
FROM
(
SELECT B.branchName, A.type, AVG (T.amount), COUNT(A.accNumber)
FROM Branch B, Account A, Transactions T
WHERE 
    B.branchNumber = A.branchNumber AND
    A.accNumber = T.accNumber
GROUP BY B.branchName, A.type
)

INNER JOIN

(
SELECT B1.branchName, COUNT(A1.accNumber)
FROM Account A1, Branch B1
WHERE 
      A1.branchNumber = B1.branchNumber 
GROUP BY B1.branchName
HAVING COUNT(A1.accNumber) > 5
)
ON
 B.branchName = B1.branchName

Answer 1

为了使查询工作，您需要命名内部选择（子查询）：

SELECT * 
FROM
(
SELECT B.branchName, A.type, AVG (T.amount), COUNT(A.accNumber)
FROM Branch B, Account A, Transactions T
WHERE 
    B.branchNumber = A.branchNumber AND
    A.accNumber = T.accNumber
GROUP BY B.branchName, A.type
) q1

INNER JOIN

(
SELECT B1.branchName, COUNT(A1.accNumber)
FROM Account A1, Branch B1
WHERE 
      A1.branchNumber = B1.branchNumber 
GROUP BY B1.branchName
HAVING COUNT(A1.accNumber) > 5
) q2
ON
 q1.branchName = q2.branchName

Answer 2

您应该为每个子查询设置名称列。试试这个：

SELECT * 
FROM
(
   SELECT B.branchName, A.type, AVG (T.amount) AS [AVG], COUNT(A.accNumber) AS [COUNT]
   FROM Branch B, Account A, Transactions T
   WHERE 
       B.branchNumber = A.branchNumber AND
       A.accNumber = T.accNumber
   GROUP BY B.branchName, A.type
) AS T1   
INNER JOIN   
(
   SELECT B1.branchName, COUNT(A1.accNumber) AS [COUNT]
   FROM Account A1, Branch B1
   WHERE 
      A1.branchNumber = B1.branchNumber 
   GROUP BY B1.branchName
   HAVING COUNT(A1.accNumber) > 5
) AS T2
ON
 T1.branchName = T2.branchName