Question

I have these two queries

select 
    t . *, events.event_time as last_time
from
    events,
(
    (
        select 
            bonding.type,
                bonding.global_id2 as target_post,
                bonding.target_id as on_whose_post,
                GROUP_CONCAT(bonding.shooter_id) as shooter_ids,
                GROUP_CONCAT(bonding.what_global_id) as shooted_what,
                MAX(bonding.what_global_id) as last,
                'bonding' as flag
        from
            bonding
        where
            bonding.type = 1
                and bonding.shooter_id in (select 
                    `user2`
                from
                    relation_table
                where
                    `user1` = 192)
        group by bonding.global_id2
    ) 
    union 
    (
    select 
            bonding.type,
                bonding.global_id2 as target_post,
                bonding.target_id as on_whose_post,
                GROUP_CONCAT(bonding.shooter_id) as shooter_ids,
                GROUP_CONCAT(bonding.what_global_id) as shooted_what,
                MAX(bonding.what_global_id) as last,
                'bonding' as flag
        from
            bonding
        where
            bonding.type = 2
                and bonding.shooter_id in (select 
                    `user2`
                from
                    relation_table
                where
                    `user1` = 192)
        group by bonding.global_id2
    ) 
    union 
    (
    select 
            bonding.type,
                bonding.global_id2 as target_post,
                bonding.target_id as on_whose_post,
                GROUP_CONCAT(bonding.shooter_id) as shooter_ids,
                GROUP_CONCAT(bonding.what_global_id) as shooted_what,
                MAX(bonding.what_global_id) as last,
                'bonding' as flag
        from
            bonding
        where
            bonding.type = 5
                and bonding.shooter_id in (select 
                    `user2`
                from
                    relation_table
                where
                    `user1` = 192)
        group by bonding.global_id2
    ) 
    union 
    (
    select 
            bonding.type,
                bonding.global_id2 as target_post,
                bonding.target_id as on_whose_post,
                GROUP_CONCAT(bonding.shooter_id) as shooter_ids,
                GROUP_CONCAT(bonding.what_global_id) as shooted_what,
                MAX(bonding.what_global_id) as last,
                'bonding' as flag
        from
            bonding
        where
            bonding.type = 9
                and bonding.shooter_id in (select 
                    `user2`
                from
                    relation_table
                where
                    `user1` = 192)
        group by bonding.global_id2
    ) 
    union 
    (
    select 
            bonding.type,
                bonding.global_id2 as target_post,
                bonding.target_id as on_whose_post,
                GROUP_CONCAT(bonding.shooter_id) as shooter_ids,
                GROUP_CONCAT(bonding.what_global_id) as shooted_what,
                MAX(bonding.what_global_id) as last,
                'bonding' as flag
        from
            bonding
        where
            bonding.type = 10
                and bonding.shooter_id in (select 
                    `user2`
                from
                    relation_table
                where
                    `user1` = 192)
        group by bonding.global_id2
    )

)as t where events.global_id = t1.last

and other one :-

SELECT 
    post_stream.type,
    post_stream.ref_global_id as target_post,
    post_stream.user_id as on_whose_post,
    post_stream.user_id as shooter_ids,
    post_stream.ref_global_id as shooted_what,
    post_stream.ref_global_id as last,
    'stream' as flag,
    events.event_time as last_time
FROM
    post_stream,
    events,
    relation_table
WHERE
    events.global_id = post_stream.ref_global_id
        and post_stream.type IN (2 , 3, 7, 8)
        AND post_stream.user_id = relation_table.user2
        AND relation_table.user1 = 192

now I need to perform a join on both the queries to get combined result, but it is giving
Every derived table must have its own alias error, where I should put an alias for derived table these two queries are running with no errors when run separately.

Answer 1

The first query is about 116 lines long as formatted, and contains a 5-way UNION sub-query. Those 5 sub-queries appear to be identical apart from one value in the WHERE clause. This rewrite dramatically simplifies the SQL to:

SELECT t.type, t.target_post, t.on_whose_post, t.shooter_ids, t.shooted_what,
       t.last, t.flag, events.event_time AS last_time
  FROM events JOIN
       (SELECT bonding.type,
               bonding.global_id2 AS target_post,
               bonding.target_id AS on_whose_post,
               GROUP_CONCAT(bonding.shooter_id) AS shooter_ids,
               GROUP_CONCAT(bonding.what_global_id) AS shooted_what,
               MAX(bonding.what_global_id) AS last,
               'bonding' AS flag
          FROM bonding
         WHERE bonding.TYPE IN (1, 2, 5, 9, 10)
           AND bonding.shooter_id IN (SELECT user2 FROM relation_table WHERE user1 = 192)
         GROUP BY bonding.global_id2
        ) AS t
     ON events.global_id = t1.last

This will be much easier to combine with the second query. With further revision, I’d probably remove the bonding. prefixes since the only table in the main sub-query is bonding.

The second query should be rewritten using JOIN notation too:

SELECT p.type          AS type,
       p.ref_global_id AS target_post,
       p.user_id       AS on_whose_post,
       p.user_id       AS shooter_ids,
       p.ref_global_id AS shooted_what,
       p.ref_global_id AS last,
       'stream'        AS flag,
       e.event_time    AS last_time
  FROM post_stream    AS p
  JOIN events         AS e ON e.global_id = p.ref_global_id
  JOIN relation_table AS r ON p.user_id = r.user2
 WHERE r.user1 = 192
   AND post_stream.type IN (2 , 3, 7, 8)

Questions:

1. Are you sure that on_whose_post and shooter_ids should be from the same column?
2. Are you sure that shooted_what and last should be from the same column?

There could be valid (and not too far-fetched) reasons for doing that — but it isn’t immediately obvious.

Unfortunately, we’ve not been told how to join the data from the first query above with the second query. There seem to be quite a lot of columns in common; only the OP can determine what’s required.