✔ Umstellung auf 3-Tier-Architektur

public class BasisObject
{
		internal string select = null;
		internal string update = null;
		internal string insert = null;

		public BasisObject()
		{
		}

		public string GetSelect()
		{
			return select;
		}

		public string GetUdpate()
		{
			return update;
		}

		public string GetInsert() 
		{
			return insert;
		}
}

public class Tabelle1 : BasisObject
{
	
	public Tabelle1()
	{
		this.insert = "INSERT INTO ....";
		this.update = "UPDATE ....";
		this.select = "SELECT bla,blab FROM ...";
	}
}

public class Storage
{
	private BasisObject dbObject = null;
	private string connectionString = "";
	private SqlConnection conn = null;

	public Storage()
	{
	}

	public BasisObject DbObject 
	{
		get { return this.dbObject; }
		set { this.dbObject = value; }
	}

	private void Open() 
	{
		if (this.conn == null)
			conn = new SqlConnection(this.connectionString);
		if (this.conn.State != System.Data.ConnectionState.Open)
			this.conn.Open();
	}

	private void Close() 
	{
		if (this.conn!=null)
			conn.Close();
	}

	public void Select() 
	{
		SqlCommand com = new SqlCommand(this.dbObject.GetInsert(), conn);
		this.Open();
		com.ExecuteNonQuery();
		this.Close();
	}

	public void Insert() 
	{
	}

	public void Update() 
	{
	}
}

public void Insert(ClsBusinessLogic contactData)
    {         
      openConnection();
    
 myContacts = new MySqlCommand("INSERT INTO contact (db_user, contact_name, picture) VALUES (?dbuser, ?contact, ?picture)", myConnection);
                
      myContacts.Parameters.Add("?dbuser", DataAccess.DBUser);
      myContacts.Parameters.Add("?contact", contactData.Contact);
      myContacts.Parameters.Add("?picture", contactData.Picture);
    
      try
      {
        myContacts.ExecuteNonQuery();
      }
      catch (Exception ex)
      {
   new FrmException(ex, MyException.MessageStatus.None, MyException.ButtonStatus.Cancel, true).ShowDialog(); 
        DBLogger log = new DBLogger(DataAccess.DBUser, "ClsDataAccess", "Insert()", ex.Message);
      }
                
      closeConnection();   
    }
    
    public void GetContact(ClsBusinessLogic contactData)
    {
      openConnection();
    
 myContacts = new MySqlCommand("SELECT contact_name, picture FROM contact WHERE id = ?contactid AND db_user = ?dbuser", myConnection);
      myContacts.Parameters.Add("?contactid", contactData.Contactid);
      myContacts.Parameters.Add("?dbuser", DataAccess.DBUser);
                
      myReader = null;
      
      try
      {
        myReader.Read();
        contactData.Contact = myReader.GetString(0);
        contactData.Picture = myReader.GetString(1);
    
      }
      catch (Exception ex)
      {
        new FrmException(ex, MyException.MessageStatus.None, MyException.ButtonStatus.Cancel, true).ShowDialog();
                        
        DBLogger log = new DBLogger(DataAccess.DBUser, "ClsDataAccess", "getContact()", ex.Message);
      }
      finally
      {
        if (myReader != null) myReader.Close();
      }
    
      closeConnection();
    }

public ClsBusinessLogic()
    {
      contactData = new ClsDataAccess();
    }
    
    public String Contactid 
    {
      get { return this.contactid; }
      set { this.contactid = value; }
    }
    
    public String Contact 
    {
      get { return this.contact; }
      set { this.contact = value; }
    }
    
    public byte[] Picture 
    {
      get { return this.picture; }
      set { this.picture = value; }
    }
    
    public void Insert()
    {
      contactData.Insert(this);
    }
    
    public void GetContact()
    {
      contactData.GetContact(this);
    }

if (this.lvwContacts.SelectedItems.Count > 0)
    {
      ClsBusinessLogic contact = new ClsBusinessLogic();
      contact.Contactid = this.lvwContacts.SelectedItems[0].SubItems[0].Text;
      
      contact.GetContact();
      
      this.txtName.Text = contact.Contact;
      this.txtPosition.Text = contact.Position;
      this.txtCompany.Text = contact.Company;
    }

ClsBusinessLogic contact = new ClsBusinessLogic();
    contact.Contact = this.txtName.Text;
    contact.Picture = data;
    contact.Insert();

    	interface ISomeDomainDAO
    	{
    		void save(SomeDomainObject o);
    		void update(SomeDomainObject o);
    		void deleteByPK(long pk);
    		SomeDomainObject getByPk(long pk);
    		List findByAttribute(String someAttribute);
    	}

    	class BusinessService
    	{
    		ISomeDomainDAO someDomainDAO
    		{
    			get
    			{
    				return someDomainDAO;
    			}
    			set
    			{
    				someDomainDAO = value;
    			}
    		}
    
    		public BusinessService()
    		{
    		}
    
    		public void someBusinessMethod(long pk)
    		{
    			SomeBusinessObject bo = someDomainDAO.getByPk(pk);
    			bo.doSomeWork(1, 2, 3);
    			someDomainDAO.update(bo);
    		}
    	}

    	class SomeDomainDAOMySQLImpl : ISomeDomainDAO
    	{
    		void save(SomeBusinessObject o)
    		{
    			...
    		}
    		void update(SomeBusinessObject o)
    		{
    			...
    		}
    		void deleteByPK(long pk)
    		{
    			...
    		}
    		SomeBusinessObject getByPk(long pk)
    		{
    			...
    		}
    		List findByAttribute(String someAttribute)
    		{
    			...
    		}
    	}