title: Run Trigger INSTEAD OF INSERT if special value was on Insert data
body: <p><strong>I want to write a trigger,which runs when special data wants to insert in my table</strong>
  for example
  my tax table has two column</p>
  
  <ul>
  <li><p>1.ID</p></li>
  <li><p>2.TAXVALUE</p></li>
  </ul>
  
  <p>I want when data wants to insert in column 2.check if data was contain "euro" string, inserted cancel.I mean do any thing instead of insert...
  the data should not can be insert if contains "euro".
  please help me on this...thanks a lot. :)</p>