title: Logic to prevent insertion if there are no available slots
body: <p>I'm developing an application in ASP.NET with C# and I'm trying to figure out the best way to implement a logic statement that will stop the system from allowing another reservation to be taken if the trailer for canoes and kayaks is full.  The issue is the trailer will hold canoes and kayaks, but there's a lot of different combinations.  </p>
  
  <p>There are 5 "rows" on the trailer that count upwards vertically, and 2 "columns" that dissect the 5 rows in the middle.  I will draw you a diagram to show you what it looks like, and what boats can go where.  "C" will stand for Canoe and "K" will stand for Kayak. The trailer looks like this: </p>
  
  <pre class="lang-none prettyprint-override"><code>C only|C only  }
  ______|______  }  BOAT TRAILER
   1C\2K|1C\2K   }
  ______|______  }     
   1C\2K|1C\2K   } 
  ______|______  }
   1C\2K|1C\2K   }
  ______|______  }
  C only| C only }
  ______|______  }
  </code></pre>
  
  <p>So my question is, what's the best option as far as coding and logic is concerned to not take any more "reservations" when the trailer is full? This application will be a .aspx form that will do an insert command to SQL server taking customer information.</p>