SQL: vertically split table and create/populate keys, foreign key relationship - sql

Question

I would like to vertically split an existing (already filled with data).
Say my starting table (trip) looks like this:
ID Person Age Trip_to Date
... Alice 21 Los Angeles 2015-04-01
... Bob 35 New York 2015-03-15
... Bob 35 Chicago 2015-03-20
... Bob 35 San Francisco 2015-03-29
... Carol 29 Miami 2015-03-30
... Carol 29 Boston 2015-04-05
I would like to split this table into two tables, as it should be, one each for person and trip.
When copying each unique person into a table person, I want the automatically created uniqueidentifier column in that table person.pId (the primary key) to be copied into a newly created uniqueidentifier column trip.personid in the original table and turn that into a foreign key. (I would then delete the trip.person and trip.age column from the original table, and have the data structured as I want them.)
I thought I could use a trigger for that when I insert the person rows into the new table, like so:
CREATE TRIGGER tr_person
on person
after INSERT
as
begin
UPDATE Trip
SET personId=(SELECT i.pId from inserted i)
WHERE person=(SELECT i.person from inserted i) and age=(SELECT i.age from inserted i)
END
However, I get this:
Subquery returned more than 1 value.
This is not permitted when the subquery follows =, !=, <, <= , >, >=
or when the subquery is used as an expression.
Apparently the trigger only executes after all (potentially multiple!) inserts have been carried out, and by that time a query on inserted is no longer allowed for my SET statement.
I also thought about using an OUTPUT clause on the INSERT statement, but that wouldn't work either
Insert into person (Driver, Age)
OUTPUT inserted.pId INTO trip.personId WHERE trip.person=inserted.person AND trip.Age=inserted.Age
(Select DISTINCT Person, Age FROM Trip)
So I am wondering now, am going about this all wrong? Is there another way to automagically create the keys and relationships between the two newly split tables?
EDIT Desired result:
Table trip:
ID Trip_to Date PersonId
... Los Angeles 2015-04-01 xxxx1
... New York 2015-03-15 xxxx2
... Chicago 2015-03-20 xxxx2
... San Francisco 2015-03-29 xxxx2
... Miami 2015-03-30 xxxx3
... Boston 2015-04-05 xxxx3
Table person
pId Person Age
xxxx1 Alice 21
xxxx2 Bob 35
xxxx3 Carol 29
(The ID fields should all be uniqueidentifiers, of course)

Answer 1

Here is an idea:
First, you insert all distinct Person from Trip table to Person table:
CREATE TABLE Person(
pID UNIQUEIDENTIFIER PRIMARY KEY,
Person VARCHAR(10),
Age INT
)
INSERT INTO Person
SELECT
NEWID(), Person, Age
FROM(
SELECT DISTINCT Person, Age FROM Trip
)t
Then, add a new FK column to Trip table PersonId which references pId from the Person table:
ALTER TABLE Trip
ADD PersonId UNIQUEIDENTIFIER
FOREIGN KEY(PersonId) REFERENCES Person(pId)
Then, UPDATE the newly added FK column with values from Person table using a JOIN on Person and Age:
UPDATE t
SET PersonId = p.pID
FROM Trip t
INNER JOIN Person p
ON p.Person = t.Person
AND p.Age = t.Age
Finally, you can drop Person and Age from Trip table:
ALTER TABLE Trip DROP COLUMN Person
ALTER TABLE Trip DROP COLUMN Age
RESULT
Person
pID Person Age
------------------------------------ ---------- -----------
35815766-1634-45FF-A3F6-8194B43F3F65 Alice 21
8EB3A7CC-CED1-4DBC-98B0-99D325BC7F67 Bob 35
D0EDCEA8-3825-4693-9352-BF7A04AEFCB2 Carol 29
Trip
ID Trip_to Date PersonId
------------------------------------ -------------------- ---------- ------------------------------------
77357A57-FAAE-43DE-923E-219038B8641E Los Angeles 2015-04-01 35815766-1634-45FF-A3F6-8194B43F3F65
C1B64E81-D30A-46A9-A868-1D92C4B64B8C New York 2015-03-15 8EB3A7CC-CED1-4DBC-98B0-99D325BC7F67
21F3614A-8E76-4A64-8A0B-815D5343FC26 Chicago 2015-03-20 8EB3A7CC-CED1-4DBC-98B0-99D325BC7F67
E1DB1926-4268-4BFA-B5E0-DA603DA8E1B7 San Francisco 2015-03-29 8EB3A7CC-CED1-4DBC-98B0-99D325BC7F67
F50E45E6-E689-444B-96C1-F936CA6F3D2A Miami 2015-03-30 D0EDCEA8-3825-4693-9352-BF7A04AEFCB2
C2FA7073-79D7-42E8-B2C8-6EEDBC374002 Boston 2015-04-05 D0EDCEA8-3825-4693-9352-BF7A04AEFCB2
Side note: You should not be storing the Age of the person. Instead, store the birthdate and compute the age on the fly.