title: Excel to SQL upload operations?
body: <p>I can fetch the data from Excel sheet to SQL Database, using File upload tool in <code>c#</code>.</p>
  
  <p>My excel sheet &amp; datatable have only 3 columns like <code>name</code>, <code>address</code>, <code>phone number</code>.<br>
  I can upload more than 5 times with same excel sheet. After this operation I am gonna open my SQL database, its shows the 3 fields are continuously adding the same table repeatedly. </p>
  
  <p>my question is..  </p>
  
  <ol>
  <li>How to avoid this adding same data in same table.</li>
  <li>How to check insert data is already exists in table or not?</li>
  <li>Update only particular field in table, when I upload the excel sheet have any one field change.</li>
  </ol>