title: SQL Update based on and Select Result From Same Table
body: <p>I am going to do my best to clearly describe what I am trying to do.</p>
  
  <p>I am using a DBISAM SQL database.</p>
  
  <p>We sell t-shirts, and lots of different kinds. I am trying to update our product database with values from other products in the database. here is an sample:</p>
  
  <p>Products Table</p>
  
  <pre><code>SKU           Product      LongDesc
  01-S          01           Great Looking T-Shirt
  01-M          01           
  01-L          01
  02-S          01           
  02-M          01           Amazing Ladies T
  02-L          01
  03-32         03           Long t
  03-34         03
  03-36         03
  </code></pre>
  
  <p>I would like to write an update script that will update the <strong>LongDesc</strong> field on all <strong>SKU</strong>'s that don't have a <strong>LongDesc</strong> but I would like that to get there <strong>LongDesc</strong> from other <strong>SKU</strong>'s with the same <strong>Product</strong></p>
  
  <p>IN THE END I WOULD LIKE THE TABLE TO LOOK LIKE THIS:</p>
  
  <pre><code>SKU           Product      LongDesc
  01-S          01           Great Looking T-Shirt
  01-M          01           Great Looking T-Shirt
  01-L          01           Great Looking T-Shirt
  02-S          01           Amazing Ladies T          
  02-M          01           Amazing Ladies T
  02-L          01           Amazing Ladies T
  03-32         03           Long t
  03-34         03           Long t
  03-36         03           Long t
  </code></pre>
  
  <p>Thanks in advance for your help!</p>