title: TSQL How to update column from row in same table?
body: <p>Say I have this table schema.</p>
  
  <p>ID
  AccNo
  Amount</p>
  
  <p>Say I have this data</p>
  
  <pre><code>ID     AccNo    Amount
  1      1020     100.00
  2      2040     50.00
  </code></pre>
  
  <p>How do I write a TSQL update query to update AccNo 1020 amount column with the amount from 2040??</p>
  
  <p>Malcolm</p>