i am writing an application where i have some objects like customer, supplier, product etc.

I have written a class for the object 'supplier' and wanted to ask if this is a good design. I have put in the class the object itself, some methods for saving and deleting, ... and some static methods for example to return all suppliers or for example delete a specific supplier other than the current object.

This is my class:

using System; using System.Data; using System.Data.SqlClient; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using MyApplication.Administration.Utility; using Microsoft.SharePoint; namespace MyApplication.Administration.Model { public class Supplier { public int id { get; set; } public string name { get; set; } public int su_id { get; set; } public string su_name { get; set; } public string portal { get; set; } public string sort_order { get; set; } public bool active { get; set; } public Supplier() { } public static Supplier GetSupplier(int supplierId) { Supplier supplier = new Supplier(); Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "SELECT supplier.*, supplier_status.name AS su_name FROM supplier INNER JOIN supplier_status ON supplier.su_id = supplier_status.id WHERE supplier.id = @id"; cmd.Parameters.AddWithValue("@id", SqlDbType.Int).Value = supplierId; conn.Open(); using (SqlDataReader dr = cmd.ExecuteReader()) { if (dr.HasRows) { // Hier ggf. nur das erste Element nehmen while (dr.Read()) { supplier.id = SqlReaderHelper.GetValue<int>(dr, "id"); supplier.name = SqlReaderHelper.GetValue<string>(dr, "name"); supplier.su_id = SqlReaderHelper.GetValue<int>(dr, "su_id"); supplier.su_name = SqlReaderHelper.GetValue<string>(dr, "su_name"); supplier.portal = SqlReaderHelper.GetValue<string>(dr, "portal"); supplier.sort_order = SqlReaderHelper.GetValue<string>(dr, "sort_order"); supplier.active = SqlReaderHelper.GetValue<bool>(dr, "active"); } } else { supplier = null; } } } }); return supplier; } public static List<Supplier> GetSuppliers() { List<Supplier> supplierList = new List<Supplier>(); Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "SELECT supplier.*, supplier_status.name AS su_name FROM supplier INNER JOIN supplier_status ON supplier.su_id = supplier_status.id"; conn.Open(); using (SqlDataReader dr = cmd.ExecuteReader()) { if (dr.HasRows) { while (dr.Read()) { Supplier supplier = new Supplier(); supplier.id = SqlReaderHelper.GetValue<int>(dr, "id"); supplier.name = SqlReaderHelper.GetValue<string>(dr, "name"); supplier.su_id = SqlReaderHelper.GetValue<int>(dr, "su_id"); supplier.su_name = SqlReaderHelper.GetValue<string>(dr, "su_name"); supplier.portal = SqlReaderHelper.GetValue<string>(dr, "portal"); supplier.sort_order = SqlReaderHelper.GetValue<string>(dr, "sort_order"); supplier.active = SqlReaderHelper.GetValue<bool>(dr, "active"); supplierList.Add(supplier); } } else { supplierList = null; } } } }); return supplierList; } /// <summary> /// Create new Supplier. /// </summary> public void Save() { Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "INSERT INTO supplier (name, su_id, portal, sort_order, active) VALUES (@name, @su_id, @portal, @sort_order, @active);"; cmd.Parameters.AddWithValue("@name", SqlDbType.NVarChar).Value = name; cmd.Parameters.AddWithValue("@su_id", SqlDbType.Int).Value = su_id; cmd.Parameters.AddWithValue("@portal", SqlDbType.NVarChar).Value = portal; cmd.Parameters.AddWithValue("@sort_order", SqlDbType.NVarChar).Value = sort_order; cmd.Parameters.AddWithValue("@active", SqlDbType.Bit).Value = active; conn.Open(); cmd.ExecuteNonQuery(); } }); } /// <summary> /// Delete the Supplier itself. /// </summary> public void Delete() { Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "DELETE FROM supplier WHERE id = @id"; cmd.Parameters.AddWithValue("@id", SqlDbType.Int).Value = id; conn.Open(); cmd.ExecuteNonQuery(); } }); } /// <summary> /// Delete a Supplier by id. /// </summary> /// <param name="supplierId"></param> public static void Delete(int supplierId) { Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "DELETE FROM supplier WHERE id = @id"; cmd.Parameters.AddWithValue("@id", SqlDbType.Int).Value = supplierId; conn.Open(); cmd.ExecuteNonQuery(); } }); } /// <summary> /// Update a Supplier. /// </summary> public void Update() { Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate () { string connString = Factories.Database.GetConnectionString(); using (SqlConnection conn = new SqlConnection(connString)) { SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "UPDATE supplier SET name = @name, su_id = @su_id, portal = @portal, sort_order = @sort_order, active = @active WHERE id = @id"; cmd.Parameters.AddWithValue("@id", SqlDbType.Int).Value = id; cmd.Parameters.AddWithValue("@name", SqlDbType.NVarChar).Value = name; cmd.Parameters.AddWithValue("@su_id", SqlDbType.Int).Value = su_id; cmd.Parameters.AddWithValue("@portal", SqlDbType.NVarChar).Value = portal; cmd.Parameters.AddWithValue("@sort_order", SqlDbType.NVarChar).Value = sort_order; cmd.Parameters.AddWithValue("@active", SqlDbType.Bit).Value = active; conn.Open(); cmd.ExecuteNonQuery(); } }); } } } 

Is this a good design or how could i optimize this? What would you prefer?