How to create references through foreign key among three tables in SQL Server ?

....................................First Example.............

CREATE TABLE t_Analog(
    [AppName] [nvarchar](20) NOT NULL,
    [ItemName] [nvarchar](32) NOT NULL,
    [Value] [float] NOT NULL,
    CONSTRAINT [uc_t_Analog] UNIQUE(AppName, ItemName)
)

CREATE TABLE t_Discrete(
    [AppName] [nvarchar](20) NOT NULL,
    [ItemName] [nvarchar](32) NOT NULL,
    [Value] [bit] NOT NULL,
    CONSTRAINT [uc_t_Discrete] UNIQUE(AppName, ItemName)
)

CREATE TABLE t_Message(
    [AppName] [nvarchar](20) NOT NULL,
    [ItemName] [nvarchar](32) NOT NULL,
    [Value] [nvarchar](256) NOT NULL,
    CONSTRAINT [uc_t_Message] UNIQUE(AppName, ItemName)
)

...................Second Example............

CREATE TABLE t_AllItems(
    [id] [bigint] IDENTITY(1,1) NOT NULL,
    [itemType] [int] NOT NULL,
    [AppName] [nvarchar](20) NOT NULL,
    [ItemName] [nvarchar](32) NOT NULL,
    CONSTRAINT [pk_t_AllItems] PRIMARY KEY CLUSTERED ( [id] )
    CONSTRAINT [uc_t_AllItems] UNIQUE([id], [AppName], [ItemName])
) ON [PRIMARY]

CREATE TABLE t_Analog(
    [itemId] [bigint] NOT NULL,
    [Value] [float] NOT NULL,
    FOREIGN KEY (itemId) REFERENCES t_AllItems(id)
)

CREATE TABLE t_Discrete(
    [itemId] [bigint] NOT NULL,
    [Value] [bit] NOT NULL,
    FOREIGN KEY (itemId) REFERENCES t_AllItems(id)
)

CREATE TABLE t_Message(
    [itemId] [bigint] NOT NULL,
    [Value] [nvarchar](256) NOT NULL,
    FOREIGN KEY (itemId) REFERENCES t_AllItems(id)
)

..........Third.......................

CREATE TABLE AllItems(
    [id] [int] IDENTITY(1,1) NOT NULL,
    [itemType] [int] NOT NULL,
    [AppName] [nvarchar](20) NOT NULL,
    [ItemName] [nvarchar](32) NOT NULL,
    CONSTRAINT [pk_AllItems] PRIMARY KEY CLUSTERED ( [id] ASC )
) ON [PRIMARY]

CREATE TABLE Analog(
    [itemId] [int] NOT NULL,
    [Value] [float] NOT NULL
)

CREATE TABLE Discrete(
    [itemId] [int] NOT NULL,
    [Value] [bit] NOT NULL
)

CREATE TABLE Message(
    [itemId] [bigint] NOT NULL,
    [Value] [nvarchar](256) NOT NULL
)

ALTER TABLE [Analog] WITH CHECK ADD CONSTRAINT [FK_Analog_AllItems] FOREIGN KEY([itemId])
REFERENCES [AllItems] ([id])
GO
ALTER TABLE [Analog] CHECK CONSTRAINT [FK_Analog_AllItems]
GO

ALTER TABLE [Discrete] WITH CHECK ADD CONSTRAINT [FK_Discrete_AllItems] FOREIGN KEY([itemId])
REFERENCES [AllItems] ([id])
GO
ALTER TABLE [Discrete] CHECK CONSTRAINT [FK_Discrete_AllItems]
GO

ALTER TABLE [Message] WITH CHECK ADD CONSTRAINT [FK_Message_AllItems] FOREIGN KEY([itemId])
REFERENCES [AllItems] ([id])
GO
ALTER TABLE [Message] CHECK CONSTRAINT [FK_Message_AllItems]
GO

..............Fourth.....

CREATE TABLE t_Generic(
[AppName] [nvarchar](20) NOT NULL,
[ItemName] [nvarchar](32) NOT NULL,
[Type] [nvarchar](32) NOT NULL,
[AnalogValue] [Float] NULL,
[DiscreteValue] [bit] NULL,
[MessageValue] [nvarchar](256) NULL,
CONSTRAINT [uc_t_Generic] UNIQUE(AppName, ItemName)
)

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