title: pandas cross join no columns in common
body: <p>How would you perform a <strike>full outer join</strike> <strong>a cross join</strong> of two dataframes with no columns in common using pandas?</p>
  
  <p>In MySQL, you can simply do:</p>
  
  <pre><code>SELECT *
  FROM table_1
  [CROSS] JOIN table_2;
  </code></pre>
  
  <p>But in pandas, doing:</p>
  
  <pre><code>df_1.merge(df_2, how='outer')
  </code></pre>
  
  <p>gives an error:</p>
  
  <pre><code>MergeError: No common columns to perform merge on
  </code></pre>
  
  <hr>
  
  <p>The best solution I have so far is using <code>sqlite</code>:</p>
  
  <pre>
  import sqlalchemy as sa
  engine = sa.create_engine('sqlite:///tmp.db')
  df_1.to_sql('df_1', engine)
  df_2.to_sql('df_2', engine)
  df = pd.read_sql_query('SELECT * FROM df_1 JOIN df_2', engine)
  </pre>