title: How do you populate an SSRS TextBox with a DataSet value?
body: <p>Dear community member,</p>
  
  <p>Given a specific <em>Key</em> (e.g. "user_name"), how does one populate an SSRS <code>TextBox</code> with the corresponding <code>DataSet</code> <em>Value</em> (e.g. "John Doe")?</p>
  
  <p>Any insight you can provide would be greatly appreciated!</p>
  
  <p><strong>CONTEXT</strong></p>
  
  <ul>
  <li>SQL Server = 2008 R2</li>
  <li>IDE = Visual Studio 2012</li>
  <li><em>ReportData</em> <code>DataSet</code> contains data used to populate a <code>Tablix</code> in the body of the report</li>
  <li><em>HeaderData</em> <code>DataSet</code> contains data used to populate two <code>TextBox</code> elements in the report header
  <ul>
  <li>this <code>DataSet</code> contains two columns: <em>key</em> and <em>value</em></li>
  </ul></li>
  </ul>
  
  <p><strong>CONSTRAINTS</strong></p>
  
  <ul>
  <li>for this particular problem, I cannot simply bind the <em>HeaderData</em> <code>DataSet</code> to a <code>Tablix</code> in the report header... I have to populate <code>TextBox</code> elements</li>
  <li>If a report contains multiple <code>DataSets</code>, and you reference the <code>Fields</code> collection in an expression... you will receive a "The Value expression for the text box users an aggregate expression without scope" error.</li>
  </ul>
  
  <p><strong>SAMPLE DATA</strong></p>
  
  <p><em>HeaderData</em></p>
  
  <p>Key="camera_name", Value="Panomera - Terminal 1"</p>
  
  <p>Key="user_name", Value="John Doe"</p>