title: Oracle Apex Calendar ordering records
body: <p>I am implementing booking tool for process. There is inventory you can use - if you want to book process for a day AM and PM slot of this day is being used up. Then when calendar  is being displayed, it brings all existing bookings showing for example that this room is not available in specific period of time. </p>
  
  <p>Difficulty I am having is, that returned entries that are being displayed NOT in order so 'AM' slot after 'PM' slot. it all seem quite random it might be confusing for end user. </p>
  
  <pre><code>SELECT * FROM 
  (
  select 
  
  query to select room 1 where slot is AM
  
  UNION ALL
  
  query to select room 1 where slot is PM
  
  UNION ALL
  
  query to select room 2 ( this room can be booked only for whole day )
  
  )
  
  ORDER BY slot ASC
  </code></pre>
  
  <p>this is structure of query I used. It returns entries correctly but not in order. I presume it is due to nested select statements. </p>
  
  <p>What is the best approach to solve this problem?</p>