title: what to include in a simple inventory database
body: <p>I want to create a simple inventory system to:</p>
  
  <ul>
  <li>Keep records of stock</li>
  <li>Alert user when a product is running out of stock</li>
  <li>Track sales and purchases</li>
  <li>Alert user when a product is almost reaching its expiry date(probably 7 days before)</li>
  <li>admin to create user accounts(all users must log in).</li>
  </ul>
  
  <p>I am not really sure <strong>how many tables I should have and what to include</strong>. I have tried the following, but it doesn't seem to work:</p>
  
  <blockquote>
    <p>Sales(Serial_Number,Name,Unit,Quantity,Amount,Sale_Date)
    Purchases(Serial_Number,Name,Unit,Quantity,Amount,Purchase_Date,Expiry_Date)
    Users(Work_Id,First_Name,Last_Name,Username,Password,Confirm_Password)</p>
  </blockquote>
  
  <p>I am using visual studio 2010 and MySQL</p>