如何在SQL Server中连接3个表？

Question

I have 3 tables :

1. Transaction (ID_Transcation)
2. Transaction Detail (ID_Transaction_Detail, ID_Transaction, ID_Services)
3. Services (ID_Services, Name)

I want to get only the name of the services, based on the ID_Transaction in the Transaction table.

The table and output that I want:

Code I tried:

Select se.Name 
from Transactions as td, Services as se 
where td.ID_Transaction = 'TRA1'

But the output is displaying all the name from service table

Answer 1

select c.name 
from Transaction as a
inner join Detail as b
on a.ID_Transaction = b.ID_Transaction
inner join Services as c
on b.id_services = c.id_services;

Answer 2

Please try the following query:

select * 
from Transaction,Detail,Services 
where Transaction.ID_Transcation=Detail.ID_Transaction 
    and Services.ID_Services=Detail.ID_Services;

Answer 3

You are missing Join condition and Table Join .

Non ANSI:

SELECT se.NAME
FROM Transactions AS td
    ,Transaction_Detail det
    ,Services AS se
WHERE 
td.ID_Transaction = det.ID_Transaction
AND det. ID_Services=  se. ID_Services
AND td.ID_Transaction = 'TRA1'

ANSI:

SELECT  se.NAME
FROM Transactions AS td
INNER JOIN Transaction_Detail AS det ON td.ID_Transaction = det.ID_Transaction
INNER JOIN Services  AS se ON det. ID_Services=  se. ID_Services
WHERE td.ID_Transaction = 'TRA1'

ANSI standard Joins are preferred. They are readable and accepted over multiple RDBMS. If you use NON ANSI Join and if you forgot join condition then the result > will be CROSS JOIN