title: How can I ensure that there is one-and-only-one row in DB table?
body: <p>I would like to ensure that my MySQL table named "myTable" has one-and-only-one row.</p>
  
  <p>So I need to be able to do Update on this row but obviously Insert and Remove should be not possible.</p>
  
  <p>I am asking this question because of this <a href="https://stackoverflow.com/questions/4617914/how-to-create-a-unique-constraint-on-a-boolean-mysql-column/4618525#4618525">Stack Overflow answer</a></p>
  
  <p>Thanks!</p>