Display Multi column in AutoComplete result using jQuery Ajax in ASP.Net

Check this example. Now please take its reference and correct your code.

You can change the format as per your choice.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

<form id="form1" runat="server">
    <asp:TextBox ID="txtName" runat="server" />
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <link rel="Stylesheet" type="text/css" href="https://code.jquery.com/ui/1.11.4/themes/start/jquery-ui.css" />
    <script type="text/javascript" src="https://code.jquery.com/ui/1.11.4/jquery-ui.min.js"></script>
    <style type="text/css">
        .ui-autocomplete {
            max-height: 320px;
            overflow-x: auto;
        }
    </style>
    <script type="text/javascript">
        $(function () {
            $("[id*=txtName]").autocomplete({
                minLength: 0,
                source: function (request, response) {
                    $.ajax({
                        url: '<%=ResolveUrl("~/Default.aspx/GetDetails") %>',
                        data: "{ 'prefix': '" + request.term + "'}",
                        dataType: "json",
                        type: "POST",
                        contentType: "application/json; charset=utf-8",
                        success: function (data) {
                            response($.map(data.d, function (item) {
                                return {
                                    label: item.split('-')[0],
                                    val: item.split('-')[1]
                                }
                            }))
                        },
                        error: function (response) {
                            alert(response.responseText);
                        },
                        failure: function (response) {
                            alert(response.responseText);
                        }
                    });
                }
            }).data("ui-autocomplete")._renderItem = function (ul, item) {
                return $("<li>")
                    .append('<a>'
                        + '<table><tr>'
                        + '<td style="width:150px">' + item.label + '</td>'
                        + '<td style="width:40px">' + item.val + '</td>'
                        + '</tr></table></a>')
                    .appendTo(ul);
            };
        });
    </script>
</form>

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;
using System.Web.Services;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient
Imports System.Web.Services

Code

C#

[WebMethod]
public static string[] GetDetails(string prefix)
{
    List<string> customers = new List<string>();
    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "SELECT CustomerId,ContactName FROM Customers WHERE ContactName LIKE @SearchText + '%'";
            cmd.Parameters.AddWithValue("@SearchText", prefix);
            cmd.Connection = conn;
            conn.Open();
            using (SqlDataReader sdr = cmd.ExecuteReader())
            {
                while (sdr.Read())
                {
                    customers.Add(string.Format("{0}-{1}", sdr["ContactName"], sdr["CustomerId"]));
                }
            }
            conn.Close();
        }
    }
    return customers.ToArray();
}

VB.Net

<WebMethod>
Public Shared Function GetDetails(ByVal prefix As String) As String()
    Dim customers As List(Of String) = New List(Of String)()
    Using conn As SqlConnection = New SqlConnection()
        conn.ConnectionString = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using cmd As SqlCommand = New SqlCommand()
            cmd.CommandText = "SELECT CustomerId,ContactName FROM Customers WHERE ContactName LIKE @SearchText + '%'"
            cmd.Parameters.AddWithValue("@SearchText", prefix)
            cmd.Connection = conn
            conn.Open()
            Using sdr As SqlDataReader = cmd.ExecuteReader()
                While sdr.Read()
                    customers.Add(String.Format("{0}-{1}", sdr("ContactName"), sdr("CustomerId")))
                End While
            End Using
            conn.Close()
        End Using
    End Using

    Return customers.ToArray()
End Function

Screeenshot