How to load PDF document from database into PDF viewer

<label>Enter the document name:</label>
<input id="documentName" />
<button id="load" onclick="loadDocument(event)" type="button">Load</button>
<div>   
    <div style="width:100%;height:950px;">
        @(Html.EJ().PdfViewer("pdfviewer").ServiceUrl("../../api/PdfViewer").PdfService(Syncfusion.JavaScript.PdfViewerEnums.PdfService.Local))
    </div>
</div>     

function loadDocument() {
        //To send the provided file name to the web API controller.
        var documentName = $("#documentName").val();
        var jsonObject = new Object();
        if (documentName != "") {
            jsonObject['documentName'] = documentName;
            var jsonResult = JSON.stringify(jsonObject);
            $.ajax({
                type: "POST",
                url: '../api/PdfViewer/DocumentRetrieve',
                crossDomain: true,
                contentType: 'application/json; charset=utf-8',
                dataType: 'json',
                data: jsonResult,
                traditional: true,
                success: function (data) {
                    //returns the PDF document data as base 64 string
                    openDoc(data);
                }
            });
        }
 
    }
    function openDoc(data) {
        var obj = $("#pdfviewer").data("ejPdfViewer");
        //load the PDF document in PDF viewer
        obj.load(data);
    }

public object DocumentRetrieve(Dictionary<string, string> jsonResult)
        {
            string documentID = jsonResult["documentName"];
            string constr = System.Configuration.ConfigurationManager.ConnectionStrings["PdfDocument"].ConnectionString;
            System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(constr);
            //searches for the PDF document from the Database
            var query = "select Data from PdfDocuments where DocumentName = '" + documentID + "'";
            System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(query);
            cmd.Connection = con;
            con.Open();
            System.Data.SqlClient.SqlDataReader read = cmd.ExecuteReader();
            read.Read();
            return "data:application/pdf;base64," + read["Data"];
        }