title: SQL Postgres display details of edges
body: <p>I have a table of nodes say</p>
  <pre><code>Table Node
  Column| type
  ------|---------------
  id    | int
  x     | int
  y     | int
  z     | text
  </code></pre>
  <p>for example,</p>
  <pre><code>id | x | y | z
  ---|---|---|---
   0 | 0 | 0 |'a'
   1 | 0 | 1 |'b'
   2 | 1 | 0 |'c'
   3 | 1 | 1 |'d'
  </code></pre>
  <p>and</p>
  <pre><code>Table Edge
  Column| type
  ------|---------------
  source| int references Node.id
  target| int references Node.id
  </code></pre>
  <p>for example,</p>
  <pre><code>source | target
  -------|-------
     0   |   1 
     1   |   3
     3   |   2
  </code></pre>
  <p>assuming a node doesn't have an edge to itself, and every source is unique</p>
  <p>I want to display the result of the entire edge information</p>
  <pre><code>source.x | source.y | target.x | target.y
  ---------|----------|----------|---------
      0    |    0     |    0     |    1
      0    |    1     |    1     |    1
      1    |    1     |    1     |    0
  </code></pre>
  <p>I have tried many joins(self join of node with inner join with edge), (left join of edge with result of self join of node)</p>
  <p>How can I achieve this selection result?</p>