title: Python Pandas read_sql - call previously specified date
body: <p>I have a sql query and I want to specify the date outside of the where query so it can be changed as needed. The following code isn't working and I'm not sure what else to try.</p>
  
  <pre><code>startdate='2018-01-01'
  
  test=pd.read_sql("""select * from database.table where date &gt; :startdate ; """ , connection)
  </code></pre>