Create a sql function that Add two value from two joint table and place it in the master table

I have the following table:   and I would like to write a function  that take the value  LocId Int Foreign key to LocTable and
DeptId Int Foreign key to DeptTable and add these two value such as A + ' ' + B and insert this value in a new column table.

([dbo].[AddTwoValuesPhone]([Location],[Department]))

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USE [ztools]
GO
/****** Object:  UserDefinedFunction [dbo].[AddTwoValuesPhone]    Script Date: 10/29/2014 16:39:07 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		<GUYON, Yves>
-- Create date: <200141027, ,>
-- Description:	<Phone Book, ,>
-- =============================================
ALTER FUNCTION [dbo].[AddTwoValuesPhone](@Location NVARCHAR(100),@Department NVARCHAR(150))

RETURNS NVARCHAR(150)
AS
 BEGIN
        DECLARE @Result NVARCHAR(150)
        SET @Result = @Location + ' - ' +  @Department   
        RETURN 
        (

            @Result
        )
    END

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Client Table
ClientID Int
Name NVARCHAR(100)
LastName  NVARCHAR(100
LocId Int Foreign key to LocTable
DeptId Int Foreign key to DeptTable
LocId   This should be a value from the following table

DeptTable
Id
Name

LocTable
Id
Name