title: How to remove duplicate in combobox with database access
body: <p>I have a database like this:</p>
  
  <pre><code>Manufacture     Model No   Length  Width  Height 
  
  Manufacture 1   MD-01      200     300    100
  Manufacture 1   MD-02      300     400    100
  Manufacture 1   MD-03      400     300    150
  Manufacture 2   MAD-01     200     450    100
  Manufacture 2   MAD-02     250     400    100
  Manufacture 3   MDI-01     300     300    100
  Manufacture 4   MOv-01     350     300    100
  </code></pre>
  
  <p>I would like to create 2 comboboxes, <em>Manufacture</em> and <em>Model No</em>.</p>
  
  <p><em>Manufacture</em> should display for the above example: Manufacture 1, Manufacture 2,Manufacture 3, Manufacture 4</p>
  
  <p>When a particular manufacture is selected for example Manufacture 2 -> The <em>Model No</em> combobox should display only MAD-01 and MAD 02.</p>
  
  <p>Based on both selections a text box must be loaded with length, width, height.</p>
  
  <p>I tried sample code and assign the combobox with database values. I got duplicate values like this:</p>
  
  <p>Manufacture 1<br />
  Manufacture 1<br />
  Manufacture 1<br />
  Manufacture 2<br />
  Manufacture 2<br /> 
  Manufacture 3<br />
  Manufacture 4 </p>
  
  <p>How can I do this correctly?</p>