SQL Server - 如何将一对多组合到一个表中

Question

我有一个联系人列表，希望能够连接到 contacts_phone 表，该表具有给定联系人的任意数量的电话。但是当我查询时，我想要一个包含所有可用电话号码的联系人列表。这可能吗？

联系人表

id	FirstName	LastName	etc
1	Liam	Smith
2	Noah	Johnson
3	Oliver	Williams

Contacts_Phone 表

id	ContactsId	Phone	PhoneType
1	1	212-555-1234	Home
2	1	212-555-2314	Cell
3	2	332-555-1324	Cell
4	3	212-555-1432	Cell
5	3	332-555-4213	Work Cell
6	3	347-555-4321	Work
7	3	212-555-4231	Alt

想要的结果

id	FirstName	LastName	etc	Phone1	Phone2	Phone3	Phone4
1	Liam	Smith		212-555-1234	212-555-2314
2	Noah	Johnson		332-555-1324
3	Oliver	Williams		212-555-1432	332-555-4213	347-555-4321	212-555-4231

Answer 1

您将需要更复杂的动态 SQL 解决方案来获得完全符合您要求的结果。

但是，这里有一个可能适合您的非动态 SQL 解决方案。它基本上是为每种手机类型使用一个子查询。

select c.id, c.FirstName, c.LastName, c.etc, 
  (select Phone from Contacts_Phone as cp where cp.ContactsId = c.id and PhoneType = 'Home') as HomePhone,
  (select Phone from Contacts_Phone as cp where cp.ContactsId = c.id and PhoneType = 'Cell') as CellPhone,
  (select Phone from Contacts_Phone as cp where cp.ContactsId = c.id and PhoneType = 'Work Cell') as WorkCellPhone,
  (select Phone from Contacts_Phone as cp where cp.ContactsId = c.id and PhoneType = 'Work') as WorkPhone,
  (select Phone from Contacts_Phone as cp where cp.ContactsId = c.id and PhoneType = 'Alt') as AltPhone 
from Contacts as c