[WebMethod]
    public string InsertStudent(string Name, string Gender, string City)
    {
        operation oper = new operation();
        string query = string.Empty;
        try
        {
            oper.Trans_Begin();
            query = @"SELECT MAX(ID)+1 AS ID FROM TBLSTUDENTS";
            int id = Convert.ToInt32(oper.DTSET(query).Tables[0].Rows[0]["ID"].ToString());
            query = string.Empty;
            query = @"INSERT INTO  TBLSTUDENTS VALUES('" + id + "','" + Name + "','" + Gender + "','" + City + "')";
            oper.sqinsert(query);
            oper.Trans_Commit();
            return query;
        }
        catch(Exception ex)
        {
            oper.Trans_Rollback();
            return "error";
        }
    }
 
 my angular code is 
 
 
 $scope.Save = function () {
        let name=$scope.studentname,gender=$scope.studentgender,city=$scope.studentcity;
        let datalist=JSON.stringify({Name:name,Gender:gender,City:city});
          $http({
            url: "Student.asmx/InsertStudent",
            method: "post",
            headers: {
                "Content-Type": "application/json; charset=utf-8",
                "dataType": "json"
            },
           data: datalist
        }).then(function (response) {
            $scope.message = "Saved Sucessfully";
        }), function (reason) {
            $scope.message = reason.data;
        }
  i am getting internal server error please help 
 
here is the example 
 
https://groups.google.com/forum/#!topic/firebase-angular/6wLh5oAnpak 
 
for my problem