Re: Help on SQL query

From: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
To: Ian Tan <iantan1268(at)gmail(dot)com>
Cc: pgsql-sql(at)lists(dot)postgresql(dot)org
Subject: Re: Help on SQL query
Date: 2019-02-15 17:28:34
Message-ID: 87k1i1klp2.fsf@news-spur.riddles.org.uk
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>>>>> "Ian" == Ian Tan <iantan1268(at)gmail(dot)com> writes:

Ian> How do I write an SQL query so that the "name" text in car_parts
Ian> are added to the bill_of_materials table, so that it looks like
Ian> this:

The only trick with this is that you need to join the car_parts table
twice (once for parent and once for child), and to do that you need to
give it different alias names:

select bom.parent_id,
ppart.name as parent_name,
bom.child_id,
cpart.name as child_name
from bill_of_materials bom
join car_parts ppart on (ppart.id=bom.parent_id)
join car_parts cpart on (cpart.id=bom.child_id);

--
Andrew (irc:RhodiumToad)

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