title: How to fill a new row in oracle with previous row values
body: <p>I have a table A with below values</p>
  
  <pre><code>year  quarter price source
  2017   1       10    s
  2017   3       12    t
  2018   1       10    m
  2018   2       15    r
  </code></pre>
  
  <p>I would like to see the table as below. Yes, I would like to fill the non specified quarters with previous quarter values. </p>
  
  <p>I thought of creating a temp table B with all quarters and do a join with this table A but how can I fill the price and source fields from previous quarter.</p>
  
  <pre><code>year  quarter price  source
  2017   1       10      s
  2017   2       10      s
  2017   3       12      t
  2017   4       12      t
  2018   1       10      m
  2018   2       15      r
  </code></pre>