title: What is the equivalent PostgreSQL syntax to Oracle's CONNECT BY ... START WITH?
body: <p>In <strong>Oracle</strong>, if I have a table defined as …</p>
  
  <pre><code>CREATE TABLE taxonomy
      (
      key NUMBER(11) NOT NULL CONSTRAINT taxPkey PRIMARY KEY,
      value VARCHAR2(255),
      taxHier NUMBER(11)
      );
  ALTER TABLE
      taxonomy
  ADD CONSTRAINT
      taxTaxFkey
  FOREIGN KEY
      (taxHier)
  REFERENCES
      tax(key);
  </code></pre>
  
  <p>With these values …</p>
  
  <pre><code>key value   taxHier
  0   zero    null
  1   one     0
  2   two     0
  3   three   0
  4   four    1
  5   five    2
  6   six     2
  </code></pre>
  
  <p>This query syntax …</p>
  
  <pre><code>SELECT
       value
  FROM
      taxonomy
  CONNECT BY
      PRIOR key = taxHier
  START WITH
      key = 0;
  </code></pre>
  
  <p>Will yield …</p>
  
  <pre><code>zero
  one
  four
  two
  five
  six
  three
  </code></pre>
  
  <p>How is this done in <strong>PostgreSQL</strong>?</p>