title: How to loop through a Table, find a value and insert if exists?
body: <p>I've two table: 
   Table A
     ID   Field1 ....</p>
  
  <p>Table B
     ID   Field2 Field3 ...</p>
  
  <p>I would like to LOOP through table B and if a a record with same ID exits in table A, add the value Field2 and Field3 in Table A.</p>
  
  <p>I don't know how to do in T-SQL!</p>