title: mysql return true if user_id exists as met_user
body: <p>I am fairly new to MYSQl.  I am trying to create a query that will fit my needs.  I have developed an   <a href="http://sqlfiddle.com/#!9/771ebf/10" rel="nofollow">sqlfiddle.</a></p>
  
  <p>Here is the story.  I have 5 tables. Users, Places, Meetings, Attend, and Met.</p>
  
  <p>In the end, I would like to be able to choose places to view what meetings are held there.  I would like to view the attendees for each meeting.  I believe I can accomplish all that pretty easily.  but...</p>
  
  <p>Here is where I am hung up.  I want to show a list of ALL users who are attending a meeting (actually, this should exclude my own id).  So one column should be user_names that list all users attending the meeting (excluding me) and another that lists who I have met shown as True or False or something similar.  So, All users from attend with specific meeting_id and True for all those from table met who have my user_id and their user_ids as met_user.</p>
  
  <p>I can achieve many different elements of mysql.  I am struggling with this one.</p>
  
  <p>Here is my schema</p>
  
  <pre><code>CREATE TABLE users (user_id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
                      user_name VARCHAR(30) NOT NULL);
  
  CREATE TABLE places (place_id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
                       place_name VARCHAR(30) NOT NULL);
  
  CREATE TABLE meetings (meeting_id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
                         place_id INT(6), 
                          meeting_name VARCHAR(30) NOT NULL);
  
  CREATE TABLE attend (attend_id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
                       meeting_id INT(6), 
                       user_id INT(6));
  
  CREATE TABLE met (met_id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,   
                    meeting_id INT(6),
                    user_id INT(6),
                    met_user INT(6));
  
  INSERT INTO users (user_name)
  VALUES ('Jason'), ('Billy'), ('Sarah'), ('Julie'), ('Jennifer'), ('Laura') ;
  
  INSERT INTO places (place_name)
  VALUES ('London'), ('Paris'), ('New York'), ('Rome');
  
  INSERT INTO meetings (place_id, meeting_name)
  VALUES ('1', 'London Meeting #1'), ('1','London Meeting #2'), ('2','Paris Meeting'), ('3','New York Meeting'), ('4','Rome Meeting');
  
  INSERT INTO attend (meeting_id, user_id)
  VALUES ('1', '1'), ('2','1'), ('1','2'), ('1','3'), ('1','4'), ('1','5'), ('1','6');
  
  
  INSERT INTO met (meeting_id, user_id, met_user)
  VALUES ('1', '1', '2'), ('1', '1', '3'),('1', '1', '4'), ('1', '2', '1'), ('1', '2', '3'), ('1', '2', '4');
  </code></pre>
  
  <p>Here is one of the queries that I think might be closest.</p>
  
  <pre><code>Select u.*, at.meeting_id, at.user_id, m.meeting_name, met.*
  from users as u
  JOIN attend as at
  ON at.user_id = u.user_id
  JOIN meetings as m
  ON at.meeting_id = m.meeting_id
  LEFT JOIN met as met
  ON met.user_id = at.user_id
  
  Where m.meeting_id = 1
  </code></pre>
  
  <p>This query is showing All of my (I am Jason in this example) met_users, all of billy's met_users, and null for all other attendees (which is part of what I want).</p>
  
  <pre><code>**[Results][2]**:
  | user_id | user_name | meeting_id | user_id |      meeting_name | met_id | meeting_id | user_id | met_user |
  |---------|-----------|------------|---------|-------------------|--------|------------|---------|----------|
  |       1 |     Jason |          1 |       1 | London Meeting #1 |      1 |          1 |       1 |        2 |
  |       1 |     Jason |          1 |       1 | London Meeting #1 |      2 |          1 |       1 |        3 |
  |       1 |     Jason |          1 |       1 | London Meeting #1 |      3 |          1 |       1 |        4 |
  |       2 |     Billy |          1 |       2 | London Meeting #1 |      4 |          1 |       2 |        1 |
  |       2 |     Billy |          1 |       2 | London Meeting #1 |      5 |          1 |       2 |        3 |
  |       2 |     Billy |          1 |       2 | London Meeting #1 |      6 |          1 |       2 |        4 |
  |       3 |     Sarah |          1 |       3 | London Meeting #1 | (null) |     (null) |  (null) |   (null) |
  |       4 |     Julie |          1 |       4 | London Meeting #1 | (null) |     (null) |  (null) |   (null) |
  |       5 |  Jennifer |          1 |       5 | London Meeting #1 | (null) |     (null) |  (null) |   (null) |
  |       6 |     Laura |          1 |       6 | London Meeting #1 | (null) |     (null) |  (null) |   (null) |
  </code></pre>