In PageInit():
    CrystalDecisions.Shared.ConnectionInfo connectionInfo = new CrystalDecisions.Shared.ConnectionInfo();

    connectionInfo.ServerName = qServer;
    connectionInfo.UserID = userID;
    connectionInfo.Password = password;
    // set report connection for main report
    SetDBLogonForReport(connectionInfo, crReport, qServer);
    // set report connection for any subreports
    SetDBLogonForSubreports(connectionInfo, crReport, qServer);

    // view report
    crystalReportViewer.ReportSource = crReport;
-----------
private void SetDBLogonForReport(
    CrystalDecisions.Shared.ConnectionInfo connectionInfo, 
    ReportDocument reportDocument, 
    string qServer)
{    
  Tables tables = reportDocument.Database.Tables;
     foreach (CrystalDecisions.CrystalReports.Engine.Table table in tables)
     {
        TableLogOnInfo tableLogonInfo = table.LogOnInfo;
        tableLogonInfo.ConnectionInfo = connectionInfo;
        table.ApplyLogOnInfo(tableLogonInfo);
     }
}
-------------
 
private void SetDBLogonForSubreports(
    CrystalDecisions.Shared.ConnectionInfo connectionInfo, 
    ReportDocument reportDocument, 
    string qServer)
{
  Sections sections = reportDocument.ReportDefinition.Sections;
  foreach (Section section in sections)
  {
    ReportObjects reportObjects = section.ReportObjects;
      
    foreach (ReportObject reportObject in reportObjects)
    {
      if (reportObject.Kind == ReportObjectKind.SubreportObject)
      {
        SubreportObject subreportObject = (SubreportObject)reportObject;
        ReportDocument subReportDocument = 
          subreportObject.OpenSubreport(subreportObject.SubreportName);
        SetDBLogonForReport(connectionInfo, subReportDocument, qServer);
      }
    }
  }
}