title: How do I upload to Azure Blob storage without overwriting?
body: <p>Calling UploadFromStream overwrites files by default - how can I make sure I only upload a blob if it isn't already in the container?</p>
  
  <pre><code>CloudBlockBlob blockBlob = container.GetBlockBlobReference(blobName);
  blockBlob.UploadFromStream(stream)
  </code></pre>