USE [AdventureWorks2012];
--- создадим где-нибудь таблицу
IF OBJECT_ID('[dbo].[PersonPhone]','U') IS NOT NULL   
DROP TABLE [dbo].[PersonPhone]  
CREATE TABLE [dbo].[PersonPhone](  
    [BusinessEntityID] [int] NOT NULL,  
    [PhoneNumber] nvarchar(25) NOT NULL,  
    [PhoneNumberTypeID] [int] NOT NULL,  
    [ModifiedDate] [datetime] NOT NULL)  
--- добавим колонку  
ALTER Table [dbo].[PersonPhone]  
ADD [StartDate] date NULL  
--- и скопируем данные в другую
UPDATE [dbo].[PersonPhone]
SET [StartDate] = DATEADD(day, 1, [HumanResources].[EmployeeDepartmentHistory].[StartDate])
FROM [HumanResources].[EmployeeDepartmentHistory]