SQL 服务器：select 记录，未链接到另一个表

Question

我有一张桌子：

CREATE TABLE [dbo].[CollectionSite]
(
    [SiteCode] [nvarchar](32) NOT NULL,
    [AddressId] [int] NOT NULL,
    [RemittanceId] [int] NULL,
    // additional columns
)

和一个链接表：

CREATE TABLE [dbo].[CollectionSiteAddress]
(
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](255) NULL,
    [Address1] [nvarchar](255) NULL,
    [Address2] [nvarchar](255) NULL,
    [City] [nvarchar](128) NULL,
    [State] [nvarchar](64) NULL,
    [Zip] [nvarchar](32) NULL,
)

这两个表之间的关系：

ALTER TABLE [dbo].[CollectionSite] WITH CHECK 
    ADD CONSTRAINT [FK_CollectionSite_CollectionSiteAddress_AddressId] 
        FOREIGN KEY([AddressId]) REFERENCES [dbo].[CollectionSiteAddress] ([Id])
GO

ALTER TABLE [dbo].[CollectionSite]  WITH CHECK 
    ADD CONSTRAINT [FK_CollectionSite_CollectionSiteAddress_RemittanceId]  
        FOREIGN KEY([RemittanceId]) REFERENCES [dbo].[CollectionSiteAddress] ([Id])
GO

我想 select 来自CollectionSiteAddress的所有记录，这些记录未链接到CollectionSite （既不是AddressId也不是RemittanceId ）。 我应该使用哪个请求？

我试过了：

SELECT *
FROM CollectionSiteAddress 
LEFT JOIN CollectionSite ON CollectionSiteAddress.Id = CollectionSite.AddressId 
                         OR CollectionSiteAddress.Id = CollectionSite.RemittanceId

但它从CollectionSiteAddress中选择所有记录

Answer 1

您缺少此WHERE子句：

WHERE CollectionSite.[SiteCode] IS NULL

因为您想要CollectionSiteAddress的所有不匹配行。
我使用[SiteCode]列检查它是否为NULL ，因为它在表的定义中不可为空。
所以你可以这样写你的查询（用别名缩短）：

SELECT csa.*
FROM CollectionSiteAddress csa LEFT JOIN CollectionSite cs
ON csa.Id = cs.AddressId OR csa.Id = cs.RemittanceId
WHERE cs.[SiteCode] IS NULL

或使用NOT EXISTS ：

SELECT csa.*
FROM CollectionSiteAddress csa 
WHERE NOT EXISTS (
  SELECT 1 
  FROM CollectionSite cs
  WHERE csa.Id = cs.AddressId OR csa.Id = cs.RemittanceId
)