C# tutorial-Database support: DataAdapter and DataSet objects

DataAdapter and DataSet objects



DataAdapter object can connect to a database through a Connection object. It has a method (Fill) that can fill data to a DataSet object. DataSet object stores tables and relationships among those tables in memory temporarily.

Example: Retrieve data from tblimages and populate the data to a listview control(Lstimages)

Retreive database

 

namespace CWindowGUI

{

    public partial class ImageView : Form

   

{

        public ImageView()

        {

            InitializeComponent();         

            displaydata();

  //select the first item of the listview

            Lstimages.Items[0].Selected = true;

        }

 

private void displaydata(){

        DataSet ds=new DataSet();

       

        OleDbDataAdapter ad;

       

        //Start connection

        OleDbConnection cn=new OleDbConnection();

       //Set connection string

        cn.ConnectionString="Provider=Microsoft.Jet.Oledb.4.0; Data Source="+ Application.StartupPath+ "\\dbimages.mdb";

        //open the connection

        cn.Open();

 

        //create DataAdapter object

        ad = new OleDbDataAdapter("Select * From tblimages", cn);

        //Fill data to DataSet object

        ad.Fill(ds, "tblimages");

        //clear listview

        Lstimages.Clear();

        //add columns

        addcolumns();

        int p=0;

        //populate the listview

        foreach (DataRow row in ds.Tables[0].Rows){

            addDataToList(p, row[ds.Tables[0].Columns[0]].ToString(), row[ds.Tables[0].Columns[1]].ToString());

            ++p;}

        //close the connection

        cn.Close();

        }

       

private void addcolumns(){

        Lstimages.View = View.Details;

        //disable multi selection and enable full row selection

        Lstimages.MultiSelect = false;

        Lstimages.FullRowSelect = true;

        //add 2 columns to listview--ID and Path

 

        Lstimages.Columns.Add("ID", 30, HorizontalAlignment.Center);

        Lstimages.Columns.Add("Path", 300, HorizontalAlignment.Center);

 

    }

 

 

private void addDataToList(int index , string  id, string path)

 

{

 

    ListViewItem item = new ListViewItem(id,index);

    item.SubItems.Add(path);

    Lstimages.Items.Add(item);

   

         

      

 

}

 

private void Lstimages_SelectedIndexChanged(object sender, EventArgs e)

{

    ListView.SelectedListViewItemCollection sel = Lstimages.SelectedItems;

    foreach (ListViewItem item in sel)

    {

        //view selected image

        pictureBox1.Image=Image.FromFile(item.SubItems[1].Text);

     }

   }

 }

 

}





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