Question

I have some tables that I’m joining in a query with Postgres (9).

However, as it’s a many to many relationship, I’m getting lots of records where I have a record for table A, and then the items for table B (as expected). For instance:

Car, Ford
Car, BMW
Car, VW
Bike, Yamaha
Bike, BMW
Bike, Honda

What I’m after is getting the relationship as a list:

Car, "Ford, BMW, VW"
Bike, "Yamaha, BMW, Honda"

Is this possible with Postgres in a normal query, or do I need to do something more magic?

Answer 1

select a.type,
       string_agg(b.name, ',');
from a 
  join b on a.id = b.type_id

You will need to replace the column and table names with the real ones (which you have not provided so I can’t use the correct ones here).