title: In SQL, how do I update data to the data warehouse as a daily activity?
body: <p>I'm trying to figure out how to create a strategy to <code>UPDATE</code> both the dimension and fact tables of a data warehouse, as a daily activity. </p>
  
  <p>Essentially, on the date the when the data is inserted into the operational DB, I want it to then be populated into the Dimension tables and hence Fact table.</p>
  
  <p>To do this I presume I would use the <code>SYSDATE()</code> as a part of a <code>WHERE</code> condition, but I don't know how to set the date portion of SYSDATE() to equal the day the operational data is taken. Would it be 'today'? I don't know.</p>
  
  <p>I can't even give a cogent example because i don't really know what I'm doing here.</p>
  
  <p>I've seen somewhere that if I only use the date, that the update will occur at midnight?</p>
  
  <p>I don't really know where to go next. Can anyone help?</p>