Get list from database in 3 layer model

I'm working on some testing project. For some reason I think I'm doing something wrong with the architecture. I have a simple example to show what I mean.

Database class

Imports DAO
Imports System.Data.SqlClient

Public Class PatientDB

    Dim connectionString As String = "Data Source=GSABBOZMAINPC;Initial Catalog=TestDB;Integrated Security=True"

    Public Function GetAllPatientFromDB() As List(Of PatientDAO)

        Using connection As New SqlConnection(connectionString)

            Dim list As New List(Of PatientDAO)

            Dim sqlString As String = "select * from patient ;"

            Using Command As New SqlCommand(sqlString, connection)

                connection.Open()

                Using reader As SqlDataReader = Command.ExecuteReader

                    While reader.Read

                        Dim firstName As String = reader("firstnamePT").ToString()

                        Dim Name As String = reader("naamPT").ToString()

                        Dim patient As New PatientDAO(Name, firstName)

                        list.Add(patient)

                    End While

                End Using

                Return list

            End Using

        End Using  

    End Function

End Class

PatientDAO

Public Class PatientDAO

    Private _name As String
    Private _lastname As String

    Sub New(naam As String, lastname As String)

        _name = naam
        _lastname = lastname

    End Sub

    Public ReadOnly Property Name As String
        Get
            Return _name
        End Get
    End Property

    Public ReadOnly Property Lastname As String
        Get

            Return _lastname

        End Get
    End Property

End Class

Patient

```
Imports DAO
Imports database_layer

Public Class Patient

Property naam As String

Property lastname As String

Sub New()

End Sub

Sub New(_naam As String, _lastname As String)

naam = _naam

las

Well, you were right to think you are wrong. We shouldn't need to instantiate an object with an empty constructor to something like this. This is exactly what the Shared keyword is for.

First, make your getAllPatientsInList function Shared:

Public Shared Function GetAllPatients() As List(Of Patient)
    ' method implementation
End Function

And now we can call the method without instantiating an instance of the class:

For Each item as Patient in Patient.GetAllPatients()
    ' do something with item
Next

And once we've done this, arguably, we may want to eliminate the default, zero-argument constructor.

StackExchange Code Review Q#95016, answer score: 8