title: SQL get value from next row
body: <p>I'm looking for an SQL way to get the value from the next row.</p>
  
  <p>The data I have looks like:</p>
  
  <pre><code>CUST    PROD     From_Qty    Disc_Pct
  23      Brush    1           0
  23      Brush    13          1
  23      Brush    52          4
  77      Paint    1           0
  77      Paint    22          7
  </code></pre>
  
  <p>What I need to end up with is this, (I want to create the To_Qty row):</p>
  
  <pre><code>CUST    PROD     From_Qty    To_Qty    Disc_Pct
  23      Brush    1           12        0
  23      Brush    13          51        1              #13 is 12+1
  23      Brush    52          99999     4              #52 is 51+1
  77      Paint    1           21        0              #1  is 99999+1
  77      Paint    22          99999     7              #22 is 21+1
  </code></pre>
  
  <p>I've got 100K+ rows to do this to, and it has to be SQL because my ETL application allows SQL but not stored procedures etc.</p>
  
  <p>How can I get the value from the next row so I can create To_Qty?</p>