title: Need help understanding alternatives to scd in SSIS
body: <p>I am working on a data warehouse project that will involve integrating data from multiple source systems. I have set up an SSIS package that populates the customer dimension and uses the slowly changing dimension tool to keep track of updates to the customer.</p>
  
  <p>I'm running into some issues. Take this example:</p>
  
  <p>Source system A might have a record like that looks like this:</p>
  
  <p>First Name, Last Name, Zipcode
  Jane, Doe, 14222</p>
  
  <p>Source system B might have a record for the same client that looks like this:</p>
  
  <p>First Name, Last Name, Zipcode
  Jane, Doe, Unknown</p>
  
  <p>If I first import the record from system A, I'll have the first name, last name, and ethnicity. Great. Now, if I import the client record from system B, I can do fuzzy matching to recognize that this is the same person and use the slowly changing dimension tool to update the information. But in this case, I'm going to lose the zipcode because the 'unknown' will overwrite the valid data. </p>
  
  <p>I am wondering if I am approaching this problem in the wrong way. The SCD tool doesn't seem to offer any way of selectively updating attributes based on whether the new data is valid or not. Would a merge statement work better? Am I making some kind of fundamental design mistake that I'm not seeing?</p>
  
  <p>Thanks for any advice!</p>