sql - SQL 查找每个客户最近的帐户交易

Question

编辑：我正在使用 SQL Server

我环顾四周寻找一个例子，但找不到任何东西，所以我将开始一个新线程......

我有 3 张桌子。

帐户

• 帐户ID
• 名
• 姓

帐户注册

• AccountEnrollID
• 帐户ID
• 帐户类型 ID
• 注册日期

帐户类型

• 帐户类型 ID
• 帐户类型

AccountEnroll 表是一个桥接表，用于跟踪每个客户的注册历史。我想使用“EnrollDate”列来确定每个客户的当前帐户类型。我需要编写一个可以显示 AccountID、FirstName、LastName、(current)AccountType 的 SELECT 语句。

我无法让我的结果集仅显示每个客户的 MAX(EnrollDate) 记录。

Answer 1

您可以使用公用表表达式非常简单地做到这一点。

with cte as (

select A.FirstName, A.LastName, AT.AccountType, AE.EnrollDate, row_number() over (partition by AE.AccountID order by EnrollDate desc) as [rn]
from Account as A
inner join AccountEnrolled as AE
   on A.AccountId = AE.AccountId
inner join AccountType as AT
   on AE.AccountTypeId = AT.AccountTypeId

)
select FirstName, LastName, AccountType, EnrollDate
from cte
where rn = 1

Answer 2

尝试这个：

SELECT 
  a.AccountID, a.FirstName, a.LastName, 
  at.AccountType AS 'Current AccountType'
FROM Account a
INNER JOIN
(
   SELECT AccountID, MAX(EnrollDate) MaxDate
   FROM AccountEnroll
   GROUP BY AccountID
) t
INNER JOIN AccountEnroll ae ON  ae.AccountID = t.AccountID 
                            AND ae.EnrollDate = t.MaxDate
INNER JOIN AccountType at ON ae.AccountTypeID = at.AccountTypeID

Answer 3

您可以使用相关的子查询：

SELECT A.AccountId, A.FirstName, A.LastName, AT.AccountType
FROM Account A
JOIN AccountEnroll AE
    ON A.AccountId = AE.AccountId
JOIN AccountType AT
    ON AE.AccountTypeId = AT.AccountTypeId
WHERE NOT EXISTS (
    SELECT 1
    FROM AccountEnroll
    WHERE AccountId = AE.AccountId
        AND EnrollDate > AE.EnrollDate
)