title: SSRS: Update text parameter based on other parameters
body: <p>I have 3 parameter in the report <code>@Start</code>, <code>@End</code>, and <code>@UserID</code> in my report.</p>
  
  <p>I want to add a 4th parameter, <code>@Parameters</code>, which is of <code>Text</code> datatype. This parameter can be null or empty. In other words, its NOT required to run the report.</p>
  
  <p>The value of the <code>@Parameters</code> should be <em>ReportName_@Start_@End_@UserID</em>.</p>
  
  <p>I have tried the default value of <code>@Parameters</code> to be</p>
  
  <p><code>=Globals!ReportName + "_" + Parameters!Start.Value + "_" + Parameters!End.Value + "_" + Parameters!UserID.Value</code></p>
  
  <p>The problem with the default value is that if I update <code>@Start</code> or <code>@End</code> or <code>@UserID</code> parameter, the value of <code>@Parameters</code> doesn't change. </p>