Re: Extend inner join to fetch not yet connected rows also - Mailing list pgsql-general

Hi Jan,

I was close and came up with:

SELECT
    craftsmanships.id,
    craftsmanships.name,
    CASE WHEN contractor_skills.user_id IS NULL THEN
        FALSE
    ELSE
        TRUE
    END AS has
FROM
    "craftsmanships"
    LEFT JOIN "contractor_skills" ON "contractor_skills"."craftsmanship_id" = "craftsmanships"."id"
    LEFT JOIN "users" ON "users"."id" = "contractor_skills"."user_id"
WHERE (contractor_skills.user_id = 3
    OR contractor_skills.user_id IS NULL)
ORDER BY
    "craftsmanships"."id”;

But after I read yours I found mine is doing lot of unnecessary joins. Thank you.


Thanks,

Arup Rakshit
ar@zeit.io



> On 22-Sep-2019, at 5:38 PM, Jan Kohnert <nospam001-lists@jan-kohnert.de> wrote:
>
> Hey,
>
> Am Sonntag, 22. September 2019, 13:21:46 CEST schrieb Arup Rakshit:
>> I have craftsmanships table which has (id, name) and users table (id, email,
>> ..). When a user has some craftsmanships, they are stored inside the
>> contractor_skills(user_id, craftsmanship_id, id) table.
>
> [...]
>
>> But I want to list all craftsmanships and has column should have `t` when
>> user_id #8 has it, else `f`. How can I extend this     query?
>
> maybe something like
>
> select
>    c.id,
>    c.name,
>    case when cs.user_id = 8 then true else false end as has
> from craftsmanships c
> left join contractor_skills cs
>    on cs.craftsmanship_id = c.craftmanship_id;
>
> --
> MfG Jan
>
>
>
>