title: connect to SQL Server using SQL alchemy without using DATABASE name
body: <p>I'm able to connect to SQL Server using SQL database name but my requirement is that I need to connect to sql server without connecting to database.</p>
  
  <p>I've the following information available with me 
  Port no., Instance name, db user/password, IP address.</p>
  
  <p>My current command is this </p>
  
  <pre><code>engine_handle = create_engine('mssql+pyodbc://sa:pass@&lt;IP address&gt;/master', echo=False)
  </code></pre>
  
  <p>Now I'm able to connect because i've given db name - master but if i remove db name and give instance name or leave it altogether. i'll get the following error.</p>
  
  <blockquote>
    <p>"engine = create_engine('mssql+pyodbc://sa:pass@IP address', echo=True)"</p>
  </blockquote>
  
  <pre><code>return self.dbapi.connect(*cargs, **cparams) DBAPIError: (Error) ('IM002', '[IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified (0) (SQLDriverConnect)') None None
  </code></pre>
  
  <p>It is ok If i can connect using instance name instead of DB name.</p>
  
  <p>any help is appreciated.</p>