INSTEAD OF Trigger is required when the view have more than one base table

CREATE TABLE ViewTableNames
(
PersonalID INT,
FirstName VARCHAR(32),
LastName VARCHAR(32)
)
GO

CREATE TABLE ViewTableAddresses
(
PersonalID INT,
Address VARCHAR(64),
City VARCHAR(32),
State CHAR(2),
Zip CHAR(5)
)
GO

CREATE TABLE ViewTablePhone
(
PersonalID INT,
PhoneType VARCHAR(32),
PhoneNumber VARCHAR(13)
)
GO
INSERT INTO ViewTableNames VALUES (101, 'Misty', 'Pfeifer')
INSERT INTO ViewTableAddresses VALUES (101, '123 4th St.',
'Anycity', 'KS', '66777')
INSERT INTO ViewTablePhone VALUES (101, 'Home', '123-456-7890')
GO

CREATE VIEW NamesView
AS
SELECT VTN.PersonalID, LastName, FirstName, Address, City, State, Zip, PhoneType, PhoneNumber 
FROM ViewTableNames VTN INNER JOIN ViewTableAddresses VTA ON (VTN.PersonalID = VTA.PersonalID)
INNER JOIN ViewTablePhone VTP ON (VTN.PersonalID = VTP.PersonalID)
GO

INSERT INTO NamesView (PersonalID, LastName, FirstName)
VALUES (102, 'Jones', 'Bill')
GO
INSERT INTO NamesView (PersonalID, Address, City, State, Zip)
 VALUES (102, '234 5th St.', 'Anycity', 'KS', '66777') -- ERROR due to more than one base table
GO
INSERT INTO NamesView (PersonalID, PhoneType, PhoneNumber)
VALUES (102, 'Cellular', '234-567-8901') -- ERROR (View or function 'NamesView' is not updatable because the modification affects multiple base tables.)
GO