Cross selection of two columns in a mysql table - php

Question

I have a mysql table consisting of users following other users. I can query what other users a specific user (me) is following, and I can also query who are following a specific user (me). These are two lists. What I cannot query is when I have a list of people following me I need to know which one of them I am following back.
It's like Tim, Peter and Suzy are following me and I follow Tim and Suzy from the 3 of them.
This is my table: the people in the USER_ID column are following the people in the FOLLOW_ID column.
Query the list of people following me: (I am the ID ending in 26):
$userid = '000000000026';
$i = 0;
try {
$stmt = $conn->prepare("SELECT USER_ID FROM FOLLOW WHERE FOLLOW_ID=?");
$stmt -> execute(array($userid));
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$row2[$i] = $row['USER_ID'];
$i++;
}
} catch(PDOException $e) {
echo 'ERROR: ' . $e->getMessage();
$response["success"] = 0;
}
for ($c=0; $c<$i; $c++) {
echo 'USER_ID FOLLOWING ME: ' . $row2[$c] . '<br>';
}
The result:
USER_ID FOLLOWING ME: 000000000030
USER_ID FOLLOWING ME: 000000000033
USER_ID FOLLOWING ME: 000000000028
So these three people are following me as you can see from the table as well.
Now I want to know which one of these three do I follow. I don't know if getting a list of the people I am following and then matching the two lists are efficient. Based on this list I follow 4 people. I see that two of them are following me (IDs ending in 28 and 33) and I want to have this information as a result.
Desired result:
USER_ID FOLLOWING ME: 000000000030, NoFollow
USER_ID FOLLOWING ME: 000000000033, Follow
USER_ID FOLLOWING ME: 000000000028, Follow
I have only mediocre knowledge of sql so please ignore advanced techniques or provide an explanation please. Thank you.

Answer 1

Try this way:
select distinct t1.user_id, t1.follow_id,
IF (t2.user_id IS NULL, 'NoFollow', 'Follow') AS Following
from test t1 left join
test t2 on ( t2.follow_id = t1.user_id
and t1.follow_id = t2.user_id)
where t1.user_id = 26
See it here on fiddle: http://sqlfiddle.com/#!2/f108c/31

Answer 2

select f1.follow_id , f2.user_id as followed_back
from follows f1 left join
follows f2 on (f2.follow_id = f1.user_id and f1.follow_id = f2.user_id)
where f1.user_id = 1
This query returns null if the user isn't following back or it's id if the user is following back
demo here
UPDATE:
new demo here. pretty much the same. if you follow back the user you get your id back. If not you get a null
select f1.user_id , f2.user_id as followed_back
from follows f1 left join
follows f2 on (f2.follow_id = f1.user_id and f1.follow_id = f2.user_id)
where f1.follow_id = 1