Use Sql Join two times on a single table - mysql

Question

This is my query in 3 Nested form. What i want is to re-write this query using JOINS but the problem is same table is repeating two times as you can see.
$query = "
SELECT
*
FROM userinfo
WHERE id IN (
SELECT DISTINCT
iduser
FROM u_n_relation
WHERE idnetwork IN (
SELECT
idnetwork
FROM u_n_relation
WHERE iduser = '$userid'
)
)
AND virtual_name LIKE CONCAT('%', ?, '%')
ORDER BY id LIMIT 5
"
What i tried was this :
$query = "
SELECT
userinfo.*
FROM userinfo
INNER JOIN u_n_relation ON (u_n_relation.iduser = userinfo.id)
WHERE
(userinfo.virtual_name LIKE CONCAT('%', ?, '%')
AND u_n_relation.iduser = '$iduser')
ORDER BY userinfo.id LIMIT 5
"
But still not getting the correct result.
Can anyone please shed some light on how to do this?
Basically what the query says is :
Fetch the details of the users who have joined the networks you have joined.

Answer 1

select distinct is not needed when you use in. However, it may be needed when you use join. Otherwise you can turn the ins into inner joins:
SELECT ui.*
FROM userinfo ui JOIN
(SELECT DISTINCT unr.iduser
FROM u_n_relation unr JOIN
u_n_relation unr2
ON unr.idnetwork = unr2.idnetwork and
unr2.iduser = '$userid'
WHERE unr.virtual_name LIKE CONCAT('%', ?, '%')
) unr
ON ui.id = unr.iduser
ORDER BY id
LIMIT 5;

Answer 2

Firstly, Mark L. is correct in that aliases are the key to JOINing the same table multiple times in a query.
Secondly, holy crap formatting. Formatting is especially important when posting your query to ask a question about it. Your formatting caused Gordon L. to mis-read which table the "virtual_name" field was in.
Initially your first query didn't make sense to me but jackkorbins comment got me to view it again and I get it this time - here it is formatted more read-ably:
SELECT *
FROM
userinfo
WHERE
id IN (-- This sub-query returns *any* iduser that is a member
-- of those same networks
SELECT DISTINCT
iduser
FROM
u_n_relation
WHERE
idnetwork IN (-- This sub-query returns the multiple networks
-- that have $userid as a member
SELECT
idnetwork
FROM
u_n_relation
WHERE
iduser = '$userid'))
AND virtual_name LIKE CONCAT('%', ?, '%')
ORDER BY
id
LIMIT 5
So another way to make a JOIN version of that query would look like:
SELECT DISTINCT
ui.*
FROM
u_n_relation unr
INNER JOIN u_n_relation net
ON (net.idnetwork=unr.idnetwork)
INNER JOIN userinfo ui
on ( ui.id = net.iduser )
WHERE
unr.iduser = '$iduser'
and ui.virtual_name LIKE CONCAT('%', ?, '%')
ORDER BY
ui.id
LIMIT 5
Sorry for my earlier confusion. :-)