Table1

AssetId  Title   DocId
1                     10
========================


Table2

DocId  Title      
=========================
5      Disaster       
10     Recovery        
15     Pending 

CREATE FUNCTION dbo.GetValue (@DocId INT)
RETURNS TABLE
AS
RETURN
    (SELECT T1.AssetId, T1.DocId, T2.Title 
     FROM Table1 T1 
        JOIN Table2 T2 
           ON T1.DocId = T2.DocId 
     WHERE T1.DocID = @DocId
    )
GO


--I was messing with this code, but its not working,  I want to be able to make Table1 Title a computed column based on Table 2 Title column and documentId

[code="sql"]
ALTER TABLE dbo.Table1
   ADD Title AS dbo.GetValue(Title) 

CREATE TABLE [dbo].[Asset](
	[AssetId] [int] NOT NULL,
	[DocId] [int] NULL,
	[Title] [nvarchar](max) NULL,
 CONSTRAINT [PK_Asset] PRIMARY KEY CLUSTERED 
(
	[AssetId] 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]

GO

CREATE TABLE [dbo].[Doc](
	[DocId] [int] NOT NULL,
	[Title] [nvarchar](max) NULL,
 CONSTRAINT [PK_Doc] PRIMARY KEY CLUSTERED 
(
	[DocId] 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]

GO

INSERT INTO [Doc]([Title]) 
	VALUES('Recovery');

INSERT INTO [Doc]([Title]) 
	VALUES('Disaster');

INSERT INTO [Doc]([Title]) 
	VALUES('Pending');

INSERT INTO [Doc]([Title]) 
	VALUES(NULL);

INSERT INTO [Asset]([DocId], [Title]) 
	VALUES(2, NULL);