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Removing recursive children

I have the following sql that will give me all the children and grandchildren root forumpost.

with recursive all_posts (id, parentid, root_id) as
                (
                select t1.id,
                t1.parent_forum_post_id as parentid,
                t1.id as root_id
                from forumposts t1

                union all

                select c1.id,
                c1.parent_forum_post_id as parentid,
                p.root_id
                from forumposts
                c1
                join all_posts p on p.id = c1.parent_forum_post_id
                )

                select fp.id
                from forumposts fp inner join all_posts ap
                on fp.id=ap.id 
                where
                root_id=1349 
                group by fp.id

I want the selected entries to be deleted. Something like delete from forumposts fp, where fp.id = (the last choice from the above code), but this does not work (I get a syntax error or next to "DELETE"). This is my first time using a recursive method and I have to miss something. Any help is appreciated.

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1 answer

You can simply use the operator DELETEinstead SELECTto do your job:

with recursive all_posts (id, parentid, root_id) as (
    select t1.id,
    t1.parent_forum_post_id as parentid,
    t1.id as root_id
    from forumposts t1

    union all

    select c1.id,
    c1.parent_forum_post_id as parentid,
    p.root_id
    from forumposts
    c1
    join all_posts p on p.id = c1.parent_forum_post_id
)
DELETE FROM forumposts
 WHERE id IN (SELECT id FROM all_posts WHERE root_id=1349);

, , .

EDIT: PostgresSQL 9.1 :

DELETE FROM forumposts WHERE id IN (
    with recursive all_posts (id, parentid, root_id) as (
        select t1.id,
        t1.parent_forum_post_id as parentid,
        t1.id as root_id
        from forumposts t1

        union all

        select c1.id,
        c1.parent_forum_post_id as parentid,
        p.root_id
        from forumposts c1
        join all_posts p on p.id = c1.parent_forum_post_id
    )
    select id from all_posts ap where root_id=1349
);
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