Re: Multiple inserts with two levels of foreign keys - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: Multiple inserts with two levels of foreign keys
Date
Msg-id 202310050939.okkrgeyg4yrs@alvherre.pgsql
Whole thread Raw
In response to Multiple inserts with two levels of foreign keys  (Dow Drake <dowdrake@gmail.com>)
Responses Re: Multiple inserts with two levels of foreign keys  (Dow Drake <dowdrake@gmail.com>)
List pgsql-general
On 2023-Oct-04, Dow Drake wrote:

> I want to insert a farm record, then insert two crops associated with that
> farm, then insert two deliveries for each of the the two crops so that in
> the end, my tables look like this:

If I understand you correctly, for each table you want one CTE with the
data you want to insert, and another CTE with the data actually
inserted, that can be matched later.  Something like this should work:

with newfarms (name) as (values ('Happy Valley Farm')),
     insertedfarms (id, name) as (insert into farms (name)
                                         select newfarms.name
                                           from newfarms
                                      returning id, name),
     newcrops (farm, name) as (values ('Happy Valley Farm', 'corn'),
                                      ('Happy Valley Farm', 'wheat')),
     insertedcrops as (insert into crops (farm_id, name)
                              select (select insertedfarms.id
                                        from insertedfarms
                                       where insertedfarms.name = newcrops.farm),
                                     newcrops.name
                                from newcrops
                           returning id, farm_id, name),
     newdeliveries (farm, name, ticket) as (values ('Happy Valley Farm', 'corn', '3124'),
                                                   ('Happy Valley Farm', 'wheat', '3127'),
                                                   ('Happy Valley Farm', 'corn', '3133'),
                                                   ('Happy Valley Farm', 'wheat', '3140')),
     inserteddeliveries as (insert into deliveries (crop_id, ticket)
                                   select (select ics.id
                                             from insertedfarms ifs join insertedcrops ics on (ifs.id = ics.farm_id)
                                            where ifs.name = newdeliveries.farm and
                                                  ics.name = newdeliveries.name),
                                          ticket
                                     from newdeliveries
                                returning *)
select * from inserteddeliveries;


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Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
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