title: use OR in hdfstore select pandas
body: <p>I know how to use AND type of query in pandas HDFStore.select, but how can I use OR?</p>
  
  <p>for example, I have the following code</p>
  
  <pre><code>import pandas as pd
  df1 = pd.DataFrame({'A': randn(100),
                  'B': randn(100),
                  'C': randn(100).cumsum()},
                  index=pd.bdate_range(end=pd.Timestamp('20131031 23:59:00'), periods=100))
  df1.to_hdf('testHDF.h5', 'testVar1', format='table', data_columns=True, append=True)
  </code></pre>
  
  <p>Then I can use the following to partially load from this dataset</p>
  
  <pre><code>store = pd.HDFStore('testHDF.h5')
  store.select('testVar1', [pd.Term('index', '&gt;=', pd.Timestamp('20131017')), 'A &gt; 0'])
  </code></pre>
  
  <p>or</p>
  
  <pre><code>store.select('tableVar2', where=('A &gt; 0', 'B &gt; 0', 'index &gt;= 20131017'))
  </code></pre>
  
  <p>Apparently, it is using AND to combine all the criteria I provided, such as ('A > 0' AND 'B > 0' AND 'index >= 20131017')</p>
  
  <p>My question is, how can I use OR, such as the returned result is ('A > 0' OR 'B > 0')?  </p>
  
  <p>Thanks for any help</p>