title: what does parameterIndex mean in this syntax pst.setString(parameterIndex, x);?
body: <p>I have a code as follow:</p>
  
  <pre><code>String query = "select * from EmployerData where userName = ? and password = ?";
  PreparedStatement pst = connect.prepareStatement(query);
  pst.setString(1, textField.getText());   // what 1 refers to
  pst.setString(2, passwordField.getText());  // 2
  </code></pre>
  
  <p>which is working perfectly as I want but I get confused about the meaning of parameterIndex. What does parameterIndex mean???</p>