Question

So I need to select a value from my table and modify it slightly to use as a value in a new row in the same table when inserting. See below:

INSERT INTO reservationbody(
    reservationid,
    driverid,
    tripnumber,
    fromlocation,
    tolocation
)
VALUES(
    1,
    2,
    (
        SELECT
           MAX(tripnumber) + 1
        FROM reservationbody
        WHERE reservationid = 1
    ),
    'here',
    'there'
)

I’m getting the following error:

You can’t specify target table ‘reservationbody’ for update in FROM
clause

I’ve had a look at other questions and have found plenty of questions on this error but they all seem to be about updates and deletes and all require PK values that already exist. None deal with inserting.

Basically what I’m expecting here is that if SELECT MAX(tripnumber) FROM reservationbody where reservationid = 1 returns a value of 4 then the insert should add a new row with a tripnumber value of 5

Can anyone suggest how I can accomplish this?

Answer 1

Have you tried (I know you can do this in MS SQL):

INSERT INTO reservationbody(reservationid,driverid,tripnumber,
                                       fromlocation,tolocation)
SELECT 1, 2, MAX(tripnumber) + 1, 'here', 'there'
FROM reservationbody
WHERE reservationid = 1