带有 3 个表的 SQL 内连接？
我正在尝试在一个视图中加入 3 个表；情况如下：
我有一张表格，其中包含申请住在这所大学校园的学生的信息。我有另一个表格，列出了每个学生的 Hall Preferences（其中 3 个）。但是这些偏好中的每一个都只是一个ID号，并且ID号在第三张表中有对应的Hall Name（不是设计这个数据库......）。
几乎，我有 INNER JOIN 他们的偏好和他们的信息，结果类似于......
John Doe | 923423 | Incoming Student | 005
其中 005 将是 HallID。所以现在我想将该 HallID 匹配到第三个表，该表包含一个 HallID 和 HallName。
非常多，我希望我的结果像......
John Doe | 923423 | Incoming Student | Foley Hall <---(INSTEAD OF 005)
这是我目前拥有的：
SELECT
s.StudentID, s.FName,
s.LName, s.Gender, s.BirthDate, s.Email,
r.HallPref1, r.HallPref2, r.HallPref3
FROM
dbo.StudentSignUp AS s
INNER JOIN RoomSignUp.dbo.Incoming_Applications_Current AS r
ON s.StudentID = r.StudentID
INNER JOIN HallData.dbo.Halls AS h
ON r.HallPref1 = h.HallID
您可以执行以下操作（我猜是表格字段等）
SELECT s.studentname
, s.studentid
, s.studentdesc
, h.hallname
FROM students s
INNER JOIN hallprefs hp
on s.studentid = hp.studentid
INNER JOIN halls h
on hp.hallid = h.hallid
根据您对多个大厅的要求，您可以这样做。您只需为每个房间 pref id 多次加入 Hall 表：
SELECT s.StudentID
, s.FName
, s.LName
, s.Gender
, s.BirthDate
, s.Email
, r.HallPref1
, h1.hallName as Pref1HallName
, r.HallPref2
, h2.hallName as Pref2HallName
, r.HallPref3
, h3.hallName as Pref3HallName
FROM dbo.StudentSignUp AS s
INNER JOIN RoomSignUp.dbo.Incoming_Applications_Current AS r
ON s.StudentID = r.StudentID
INNER JOIN HallData.dbo.Halls AS h1
ON r.HallPref1 = h1.HallID
INNER JOIN HallData.dbo.Halls AS h2
ON r.HallPref2 = h2.HallID
INNER JOIN HallData.dbo.Halls AS h3
ON r.HallPref3 = h3.HallID
如果您有 3 个具有相同 ID 的表要加入，我认为它会是这样的：
SELECT * FROM table1 a
JOIN table2 b ON a.ID = b.ID
JOIN table3 c ON a.ID = c.ID
只需将 * 替换为您想从表格中获取的内容。
SELECT column_Name1,column_name2,......
From tbl_name1,tbl_name2,tbl_name3
where tbl_name1.column_name = tbl_name2.column_name
and tbl_name2.column_name = tbl_name3.column_name
SELECT table1.col,table2.col,table3.col
FROM table1
INNER JOIN
(table2 INNER JOIN table3
ON table3.id=table2.id)
ON table1.id(f-key)=table2.id
AND //add any additional filters HERE
您只需要第二个内部联接，将您现在拥有的 ID Number 链接到第三个表的 ID Number。然后，将 ID Number 替换为 Hall Name 和瞧 :)
SELECT *
FROM
PersonAddress a,
Person b,
PersonAdmin c
WHERE a.addressid LIKE '97%'
AND b.lastname LIKE 'test%'
AND b.genderid IS NOT NULL
AND a.partyid = c.partyid
AND b.partyid = c.partyid;
有很多回应，但总的教训似乎是您可以在 where 子句中使用多个 JOINS； techonthenet.com（我的老板向我推荐了它，我就是这样找到它的）也有很好的 SQL 教程，如果你还有其他问题，你只是想试着弄清楚。
SELECT table1.column1
FROM table1
WHERE table1 > 0 (or whatever you want to specify)
INNER JOIN table1
ON table1.column1 = table2.column1
这是对具有相同 ID 的连接 3 表的正确查询**
select a.empname,a.empsalary,b.workstatus,b.bonus,c.dateofbirth from employee a, Report b,birth c where a.empid=b.empid and a.empid=c.empid and b.empid='103';
员工第一张桌子。报告第二张表。出生第三张表
SELECT
A.P_NAME AS [INDIVIDUAL NAME],B.F_DETAIL AS [INDIVIDUAL FEATURE],C.PL_PLACE AS [INDIVIDUAL LOCATION]
FROM
[dbo].[PEOPLE] A
INNER JOIN
[dbo].[FEATURE] B ON A.P_FEATURE = B.F_ID
INNER JOIN
[dbo].[PEOPLE_LOCATION] C ON A.P_LOCATION = C.PL_ID
此查询将为您工作
Select b.id as 'id', u.id as 'freelancer_id', u.name as
'free_lancer_name', p.user_id as 'project_owner', b.price as
'bid_price', b.number_of_days as 'days' from User u, Project p, Bid b
where b.user_id = u.id and b.project_id = p.id
select products.product_id, product_name, price, created_at, image_name, categories.category_id, category_name,brands.brand_id, brand_name
FROM products INNER JOIN categories USING (category_id) INNER JOIN brands USING(brand_id)
select empid,empname,managename,[Management ],cityname
from employees inner join Managment
on employees.manageid = Managment.ManageId
inner join CITY on employees.Cityid=CITY.CityId
id name managename managment cityname
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1 islam hamza it cairo
