SQL Server foreign key data issue - sql-server

Question

I have 3 tables
crm.Documents
crm.GroupDocuments
schedular.Groups
Documents table looks like
Id Name
-----------
1 Test
GroupDocuments table looks like
Id | GroupId | DocumentId
---+---------+------------
1 | 1 | 1
2 | 2 | 1
Group table looks like
Id | Name
---+--------
1 | Sales
2 | Service
3 | Techs
The code to create these tables is :
CREATE TABLE [crm].[Documents]
(
[Id] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](100) NOT NULL,
[FileType] [int] NOT NULL,
[Bytes] [varbinary](max) NOT NULL,
[IsShared] [bit] NOT NULL,
[UploadDate] [datetime2](7) NOT NULL,
[LastSaveDate] [datetime2](7) NOT NULL,
CONSTRAINT [PK_Documents]
PRIMARY KEY CLUSTERED ([Id] ASC)
WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
CREATE TABLE [scheduler].[Groups]
(
[Id] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NULL,
CONSTRAINT [PK_Groups]
PRIMARY KEY CLUSTERED ([Id] ASC)
WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
CREATE TABLE [crm].[GroupDocuments]
(
[GroupId] [int] NOT NULL,
[DocumentId] [int] NOT NULL,
CONSTRAINT [PK_GroupDocuments]
PRIMARY KEY CLUSTERED ([GroupId] ASC, [DocumentId] ASC)
WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [crm].[GroupDocuments] WITH CHECK
ADD CONSTRAINT [FK_GroupDocuments_Documents_GroupId]
FOREIGN KEY([GroupId]) REFERENCES [crm].[Documents] ([Id])
ON DELETE CASCADE
GO
ALTER TABLE [crm].[GroupDocuments] CHECK CONSTRAINT [FK_GroupDocuments_Documents_GroupId]
GO
ALTER TABLE [crm].[GroupDocuments] WITH CHECK
ADD CONSTRAINT [FK_GroupDocuments_Groups_DocumentId]
FOREIGN KEY([DocumentId]) REFERENCES [scheduler].[Groups] ([Id])
ON DELETE CASCADE
GO
ALTER TABLE [crm].[GroupDocuments] CHECK CONSTRAINT [FK_GroupDocuments_Groups_DocumentId]
GO
When I run
INSERT INTO crm.GroupDocuments (GroupId, DocumentId)
VALUES (3, 1)
I get this error:
Msg 547, Level 16, State 0, Line 1
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_GroupDocuments_Documents_GroupId".
The conflict occurred in database "Scheduler", table "crm.Documents",
column 'Id'.
There is an Id 3 on the group table and an Id 1 on the documents table. Can someone please explain why this error would occur?

Answer 1

You have inverted your FOREIGN KEY references....
ALTER TABLE [crm].[GroupDocuments]
ADD CONSTRAINT [FK_GroupDocuments_Documents_GroupId]
FOREIGN KEY([**GroupId**]) REFERENCES [crm].[**Documents**] ([Id])

Answer 2

You've criss-crossed the referenced columns in the definition of your foreign key constraints .... your DocumentID references Groups.Id, while GroupId references Documents.Id....
Change your FK statements to:
-- "GroupId" should reference "Groups.Id" (not "Documents.Id") .....
ALTER TABLE [crm].[GroupDocuments] WITH CHECK
ADD CONSTRAINT [FK_GroupDocuments_GroupId]
FOREIGN KEY([GroupId]) REFERENCES [scheduler].[Groups]([Id])
ON DELETE CASCADE
GO
-- and "DocumentId" should reference "Documents.Id" (not "Groups.Id")
ALTER TABLE [crm].[GroupDocuments] WITH CHECK
ADD CONSTRAINT [FK_GroupDocuments_DocumentId]
FOREIGN KEY([DocumentId]) REFERENCES [crm].[Documents]([Id])
ON DELETE CASCADE
GO