sql - MySQL How to account for blocked users when returning comments -

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i thought had solved problem, realised specifying user not friends in friends table cause user not able see posts, not behaviour want.

a blocked user has category of 4. i'm aware return comments post , manually check if category of user 4, un-necessary computation solved single query (i think).

select distinct   ent.entity_id,   ent.profile_pic_url,   ent.first_name,   ent.last_name,   ent.last_checkin_place,   comments.content,   friends.category   checkin_comments comments   join entity ent     on comments.entity_id = ent.entity_id   join friends      on comments.entity_id = friends.entity_id1       or comments.entity_id = friends.entity_id2   comments.chk_id = 1726   , friends.category != 4 group comments.comment_id

this return results, because there no way specify logged in user. thought supply sub-query:

select distinct   ent.entity_id,   ent.profile_pic_url,   ent.first_name,   ent.last_name,   ent.last_checkin_place,   comments.content,   friends.category   checkin_comments comments   join entity ent     on comments.entity_id = ent.entity_id   join friends      on comments.entity_id = friends.entity_id1       or comments.entity_id = friends.entity_id2   comments.chk_id = 1726   , friends.category = (       select category friends               friends.entity_id1 = 1527         , friends.entity_id2 = comments.entity_id         or friends.entity_id1 = comments.entity_id         , friends.entity_id2 = 1527     )   -- filter out blocked users have category of 4   , friends.category != 4    group comments.comment_id

the idea here fetch category of each user , filter result set based on that, sort of worked, in sense returns list of users friends, not account use case when comment made non-friend (who won't exist in friends table).

how can fix query users returned, , users have category of 4 not shown?

if need more information please ask.

you're looking outer join. variant of first query should trick:

select distinct   ent.entity_id,   ent.profile_pic_url,   ent.first_name,   ent.last_name,   ent.last_checkin_place,   comments.content,   friends.category   checkin_comments comments   join entity ent     on comments.entity_id = ent.entity_id   left join friends      on comments.entity_id = friends.entity_id1       or comments.entity_id = friends.entity_id2   comments.chk_id = 1726   , ifnull(friends.category, 0) != 4 group comments.comment_id

in event comment author not associated requester via friends table, comment included in join result, columns derived friends being null. ifnull() in where clause deals converting null category value 0 (though in fact value other 4 work).


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