使用 NOT IN / NOT EXISTS(?) 和三个表的 SQL 查询的结构

Question

我需要帮助找出查询的正确结构

find the names of those clients, who stopped in exactly the same hotels as John Doe.

我有桌子：

Clients(clientID, clientName)

ClientTour(clientID, tourID)

Tours(tourID, country, hotel)

全部写成一个查询。

我对 SQL 很陌生，不能为它写下正确的子查询，因为它使用三个表...我有点了解如何为两个表编写类似的查询，但是当我试着写这个……好吧，我迷路了。 =/

据我所知，我必须找到那些客户的名字，谁停在

[John Doe 停靠的所有酒店] - [只有 John Doe 停靠的酒店]

但谁从未停止过那些

[李四从未下榻的酒店]。

逻辑上对吗？如果是，那么我得到的部分是

SELECT c1.clientName

FROM Clients c1

WHERE c1.clientID NOT IN (clientIDs of clients in [Hotels where John Doe never stopped])

AND c1.clientID IN (clientIDs of clients in [[All Hotels where John Doe stopped] - [Hotels where only John Doe stopped]])

但无法弄清楚以斜体标记的部分...我如何找到曾在 John Doe did/didn 未下榻的酒店或仅 John Doe 下榻的酒店下榻的客户？

另外，有没有更简单的方法来写下这个查询？

Answer 1

编辑：
1. 在外层SELECT增加了一个GROUP BY子句，取代了DISTINCT的需要，并在结果中为每个客户增加了countnig家酒店的选项设置。请注意，结果集仅包含 'John Doe' 入住过的酒店。
2. 添加了一个 SELECT 语句来计算 'John Doe' 访问过的酒店数量。
3. 添加了一个 HAVING 子句以从结果集中删除酒店数量不同于 'John Doe'.

的客户

SELECT C.clientName 
FROM (Clients AS C INNER JOIN ClientTour AS CT ON C.clientID = CT.clientID) INNER JOIN Tours AS T ON CT.tourID = T.tourID
WHERE C.clientName <> 'John Doe' 
    AND T.hotel IN 
(
    SELECT DISTINCT T1.hotel
    FROM (Clients AS C1 INNER JOIN ClientTour AS CT1 ON C1.clientID = CT1.clientID) INNER JOIN Tours AS T1 ON CT1.tourID = T1.tourID
    WHERE C1.clientName = 'John Doe' 
)
GROUP BY C.clientName 
HAVING COUNT(DISTINKT T.hotel) = SELECT COUNT(DISTINCT T2.hotel)
    FROM (Clients AS C2 INNER JOIN ClientTour AS CT2 ON C2.clientID = CT2.clientID) INNER JOIN Tours AS T2 ON CT2.tourID = T2.tourID
    WHERE C2.clientName = 'John Doe'

第一次尝试：

SELECT C.clientName 
FROM (Clients AS C INNER JOIN ClientTour AS CT ON C.clientID = CT.clientID) INNER JOIN Tours AS T ON CT.tourID = T.tourID
WHERE Trim(C.clientName) <> 'John Doe' 
    AND T.hotel IN 
(
    SELECT DISTINCT T1.hotel
    FROM (Clients AS C1 INNER JOIN ClientTour AS CT1 ON C1.clientID = CT1.clientID) INNER JOIN Tours AS T1 ON CT1.tourID = T1.tourID
    WHERE Trim(C1.clientName) = 'John Doe' 
)

使用 NOT IN / NOT EXISTS(?) 和三个表的 SQL 查询的结构

Structure of SQL query using NOT IN / NOT EXISTS(?) with three tables

sql

ms-access

multiple-tables