how to check the textbox value user enter the value in textbox is right or wrong using ajax Jquery? – Jquery ajax

I m working with ajax jquery Search Functionality.

when I search the record in textbox then get the record but when I search false record then get the false record? that is the issue

table:

Emploee.aspx

                  <tr>
                    <td>
                        Search Record:   <asp:TextBox ID="txtsearch" runat="server"></asp:TextBox>
                                         <input id="btnsearch" type="button" value="Search" onclick="searchrecord()" />
                    </td>
                </tr>           
            </table>
        </div>

        <div class="row">
            <div>
                <table id="tbl" border="1">
                    <thead>
                        <tr>
                            <th>StudentName</th>
                            <th>StudentAddress</th><br /><br />
                            <th>Edit</th>
                        </tr>
                    </thead>
                </table>
            </div>
        </div>



       function searchrecord(studname) {

                jQuery.ajax({
                    url: "WebForm1.aspx/search",
                    type: 'post',
                    contentType: 'application/json;charset=utf-8',
                    datatype: 'json',
                    data: "{ studname:'" + $("#txtsearch").val() + "' }",
                    success: function (data) {
                        debugger

                        if (data.d == $("#txtsearch").val()) {

                            debugger

                            txt = "<tr><td>" + data.d + "</td></tr>";
                            $("#tbl").append(txt);
                            alert('you enter right record');

                        }

                        else if (data.d != $("#txtsearch").val()) {

                            alert('you enter wrong record');

                        }

                    },
                    error: function () {
                        alert('search Error');  //now whatever i search then this run
                    },
                });
            }

Emploee.aspx

        [WebMethod]
        public static string search(string studname,bool flg)
        {
            string data = "";
            SqlConnection con = new SqlConnection(cn);

            SqlCommand cmd = new SqlCommand("SELECT studname FROM tblstud WHERE studname LIKE @studname and active=@flagTrueOrFalse", con);
            con.Open();

            cmd.Parameters.AddWithValue("@studname", "%" + studname + "%");
            cmd.Parameters.AddWithValue("@flag", SqlDbType.Bit).Value = flg;

            SqlDataReader reader = cmd.ExecuteReader(); 

            if (reader.HasRows)
            {
                while (reader.Read())
                {
                    studname = reader[0].ToString();
                }
            }
            else
            {
                Console.WriteLine("No rows found.");
            }

            reader.Close();
            data = studname;
            return data;
        }

how to solve if-else condition ajax logic?

main get data list:

function GetData() {
                $.ajax({

                    url: 'Emploee.aspx/GetData',
                    type: 'post',
                    contentType: 'application/json;charset=utf-8',
                    datatype: 'json',
                    success: function (data) {
                        data = JSON.parse(data.d);
                        $.each(data, function (index, element) {
                            $("#tbl").append('<td>' + element.studname + '</td>');
                            $("#tbl").append('<td>' + element.studaddress + '</td>');
                            $("#tbl").append('<td><input type="button" id="btnupdate" value="Update" onclick="Update(' + element.studid + ', '' + element.studname + '' ,'' + element.studaddress + '')" /></td>');
                        });
                    },
                    error: function (error) {
                        alert('Not Get Data')
                    },
                });
            }

simple, I want the add an if-else condition when the user enters the true record then add the record and the user gets a false record then gets the alert message box?

I want to set below condition in the above ajax:

if(textbox value match then going inside)
{
  txt = "<tr><td>" + data.d + "</td></tr>";
  $("#tbl").append(txt);
}
else if(textbox value not match then going inside)
{alert("please proper record enter");}

Console log:

preview:

{Message: "Invalid web service call, missing value for parameter: 'flg'.",…}
Message: "Invalid web service call, missing value for parameter: 'flg'."
StackTrace: "   at System.Web.Script.Services.WebServiceMethodData.CallMethod(Object target, IDictionary`2 parameters)
↵   at System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(Object target, IDictionary`2 parameters)
↵   at System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)
↵   at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)"
ExceptionType: "System.InvalidOperationException"

Response

{"Message":"Invalid web service call, missing value for parameter: u0027flgu0027.","StackTrace":"   at System.Web.Script.Services.WebServiceMethodData.CallMethod(Object target, IDictionary`2 parameters)rn   at System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(Object target, IDictionary`2 parameters)rn   at System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)rn   at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)","ExceptionType":"System.InvalidOperationException"}