title: Mysql prevent insert after some date
body: <p>Is possible prevent the insertion in a mysql table after some date and time? </p>
  
  <p>for example i have 2 tables: </p>
  
  <pre><code>TABLE exams 
  (
  ...
  examID int primary key auto_increment,
  examDate DATE,
  examTime TIME, 
  ...
  )
  
  
  TABLE inscripts
  (
  ...
  examID int not null references exams(examID),
  insDate DATE,
  insTime TIME,
  ...
  )
  </code></pre>
  
  <p><strong>i want to prevent the insertion of new inscriptions when the exam is playing.</strong></p>
  
  <p>There are some function to prevent this or check easily if current date and current time are equal or bigger than the date and time in matches table?</p>