Update the code according to Standard

Question

Using VB.Net, C#.Net and SQL Server.

Windows Application

I want to separate a code for 3 Tier Architecture(Presentation Layer, Data Access Layer, Business Logic Layer).

Code.

Form_Load

    Dim cmd As New SqlCommand
    Dim ada As New SqlDataAdapter
    Dim ds As New DataSet

    Con = New SqlConnection("Data Source='" & servername.Text & "';Initial  Catalog='"     & databasename.Text & "';Integrated Security=true")
                    Con.Open()

        cmd = New SqlCommand("Select * from tb1", Con)
        ada = New SqlDataAdapter(cmd)
        ada.Fill(ds, "tb1")
        datagrid2.DataSource = ds.Tables("tb1")

Above code is working, But i want to do a same process by using 3 Tier Architecture.

How to separate my code according to 3 tier Architecture.

Need VB.Net Code Help

Answer 1

the following codeshould be on your Presentation Layer

 Datagrid2.DataSource = ds.Tables("tb1")

the following layer should be on you Data Access Layer

 Dim cmd As New SqlCommand 
 Dim ada As New SqlDataAdapter 
 Dim ds As New DataSet 

 Con = New SqlConnection("Data Source='" & servername.Text & "';Initial  Catalog='"     & databasename.Text & "';Integrated Security=true") 
 Con.Open() 

and the following code should be onyour Business Logic Layer

cmd = New SqlCommand("Select * from tb1", Con)    
ada = New SqlDataAdapter(cmd)    
ada.Fill(ds, "tb1")

but I strongly recommand tonot use something like it, Use an ORM like NHibernate or EntityFramework or atleast from LinkToSql

Answer 2

you can make a class library project for every layer except UI layer. Then you must breakdown each process to this 3 layer. for example do every data accessing in Data Access Layer and put every logic in Logic Layer. at the UI you can't work with DAL directly. you should only call methods that defined in BLL.

Note: add these layers to UI by adding dll of per layer as reference to UI Project.

DAL

public DataSet GetData(string serverName,string dataBaseName)
{
    SqlCommand cmd;
    SqlDataAdapter ada;
    DataSet ds = new DataSet();
    SqlConnection Con;

    Con = New SqlConnection("Data Source='" & serverName & "';Initial  Catalog='"  & dataBaseName & "';Integrated Security=true");
     Con.Open();

        cmd = New SqlCommand("Select * from tb1", Con);
        ada = New SqlDataAdapter(cmd);
        ada.Fill(ds, "tb1");
        return ds;
}

BLL

public DataSet GetData(string serverName,string dataBaseName)
{
    DataSet ds = new DataSet();
    ds = DoAction(new DAL().GetData(serverName, dataBaseName)); //do something on data 
    return ds;
}

UI

datagrid2.DataSource = new BLL().GetData(servername.Text,databasename.Text);
datagrid2.DataMember = "tb1";
datagrid2.DataBind();