title: unpacking a sql select into a pandas dataframe
body: <p>Suppose I have a select roughly like this:</p>
  
  <pre><code>select instrument, price, date from my_prices;
  </code></pre>
  
  <p>How can I unpack the prices returned into a single dataframe with a series for each instrument and indexed on date?</p>
  
  <p>To be clear: I'm looking for:</p>
  
  <pre><code>&lt;class 'pandas.core.frame.DataFrame'&gt;
  DatetimeIndex: ...
  Data columns (total 2 columns):
  inst_1    ...
  inst_2    ...
  dtypes: float64(1), object(1) 
  </code></pre>
  
  <p>I'm NOT looking for:</p>
  
  <pre><code>&lt;class 'pandas.core.frame.DataFrame'&gt;
  DatetimeIndex: ...
  Data columns (total 2 columns):
  instrument    ...
  price         ...
  dtypes: float64(1), object(1)
  </code></pre>
  
  <p>...which is easy ;-)</p>