title: SQL union of two tables with different columns
body: <p>I want to get one result set of rows back from two tables with different column names, one line per line in each table.</p>
  
  <p>Result should look like this, blanks can be null, team_id in 2nd half comes from coach_id:</p>
  
  <pre><code>-----------------------------------------
  player_id | team_id | score | improvement
  -----------------------------------------
  11          20         5
  11          21         4
  12          22         2
  12          23         2
  11          20                   5
  11          21                   6
  12          21                   5
  13          23                   10
  </code></pre>
  
  <p>Here's the schema:</p>
  
  <pre><code>CREATE TABLE coaches
      (`id` int, `team_id` int)
  ;
  
  INSERT INTO coaches
      (`id`, `team_id`)
  VALUES
      (1, 20),
      (2, 21),
      (3, 22),
      (4, 23)
  ;
  
  CREATE TABLE players
   (`id` int, `player_id` int);
  
  
  INSERT INTO players
  (`id`, `player_id`)
  VALUES
  (1,11),
  (2,12),
  (3,13),
  (4,14)
  ;
  CREATE TABLE games
      (`id` int, `player_id` int, `team_id` int, `score` int)
  ;
  
  INSERT INTO games
      (`id`, `player_id`, `team_id`, `score`)
  VALUES
      (1, 11, 20, 5),
      (2, 11, 21, 4),
      (3, 12, 22, 2),
      (4, 12, 23, 2)
  ;
  
  CREATE TABLE sessions
      (`id` int, `player_id` int, `coach_id` int, `improvement` int)
  ;
  
  INSERT INTO sessions
        (`id`, `player_id`, `coach_id`, `improvement`)
  VALUES
      (1, 11, 1, 5),
      (2, 11, 2, 6),
      (3, 12, 2, 5),
      (4, 13, 4, 10)
  ;
  </code></pre>
  
  <p>Tried this, but it wasn't really close:</p>
  
  <pre><code>SELECT tweets.player_id
        ,tweets.team_id
        ,follows.coach_id 
  FROM tweets FULL OUTER JOIN follows ON (1 = 0);
  </code></pre>