ASP.NET

This is My dbAccess Class:: 
 
using System; 
using System.Collections.Generic; 
using System.Web; 
using System.Web.Configuration; 
using System.Data.SqlClient; 
using System.Data; 
using System.Web.Services; 
 
namespace Assign3_PRS 
{ 
    public class dbAccess 
    { 
        public string connectionString = @"Data Source=.\CARECENTERMD; Initial Catalog=Automation; Integrated Security=true"; 
        SqlConnection connection; 
        SqlCommand command; 
        SqlDataAdapter dataAdapter; 
        DataSet dataset; 
        DataTable datatable; 
         
         public dbAccess() 
        { 
           
        } 
 
        [WebMethod()] 
         public string Login_Check(Login login) 
         { 
             string role = string.Empty; 
 
             connection = new SqlConnection(connectionString); 
             command = new SqlCommand("CHECK_USER_PASSWD", connection); 
             command.CommandType = CommandType.StoredProcedure; 
             command.Parameters.Add("@UserName", SqlDbType.VarChar).Value = login.username; 
             command.Parameters.Add("@passWord", SqlDbType.VarChar).Value = login.password; 
             dataAdapter = new SqlDataAdapter(command); 
             datatable = new DataTable(); 
             dataAdapter.Fill(datatable); 
             if (datatable.Rows.Count > 0) 
             { 
                 role = datatable.Rows[0]["Roles"].ToString(); 
             } 
             else 
             { 
                 string NotValidUser = "NotValidUser"; 
                 return NotValidUser; 
             } 
             return role; 
         } 
 
         [WebMethod()] 
        public int Insert(Patient patient) 
        { 
            connection = new SqlConnection(connectionString); 
            connection.Open(); 
            command = new SqlCommand("SAVING_PAT_DETAILS", connection); 
            command.CommandType = CommandType.StoredProcedure; 
            try 
            { 
                command.Parameters.AddWithValue("@ID", patient.Id); 
                command.Parameters.AddWithValue("@NAME", patient.Name); 
                command.Parameters.AddWithValue("@SEX", patient.Sex); 
                command.Parameters.AddWithValue("@PROBLEM", patient.Problem); 
                command.Parameters.AddWithValue("@ADDRESS", patient.Address); 
                command.Parameters.AddWithValue("@PHONE", patient.Phone); 
                command.Parameters.AddWithValue("@PROBLEM", patient.Problem); 
                command.Parameters.AddWithValue("@COMMENTS", patient.Comments); 
 
                return command.ExecuteNonQuery(); 
            } 
            catch (Exception ex) 
            { 
                throw ex; 
            } 
            finally 
            { 
                command.Dispose(); 
                connection.Close(); 
                connection.Dispose(); 
            } 
        } 
 
         [WebMethod()] 
        public int Update(Patient patient) 
        { 
            connection = new SqlConnection(connectionString); 
            connection.Open(); 
            command = new SqlCommand("UPDATING_PAT_DETAILS", connection); 
            command.CommandType = CommandType.StoredProcedure; 
            try 
            { 
                command.Parameters.AddWithValue("@ID", patient.Id); 
                command.Parameters.AddWithValue("@NAME", patient.Name); 
                command.Parameters.AddWithValue("@SEX", patient.Sex); 
                command.Parameters.AddWithValue("@PROBLEM", patient.Problem); 
                command.Parameters.AddWithValue("@ADDRESS", patient.Address); 
                command.Parameters.AddWithValue("@PHONE", patient.Phone); 
                command.Parameters.AddWithValue("@PROBLEM", patient.Problem); 
                command.Parameters.AddWithValue("@COMMENTS", patient.Comments); 
 
                return command.ExecuteNonQuery(); 
            } 
            catch (Exception ex) 
            { 
                throw ex; 
            } 
            finally 
            { 
                command.Dispose(); 
                connection.Close(); 
                connection.Dispose();