characterized search using windows form application

Question

I have a search textbox in my windows form application and I want to search character by character means when I write h in textbox then shows result in datagridview of h and when I add h with a like ha in search textbox then shows result in datagridview of ha and its change results in datagridview from h to ha as same as mobile phone contacts searching. and I working like below:

public partial class Form2 : Form
{
    SqlConnection connection = new SqlConnection("Data Source=(LocalDB)\\v11.0;AttachDbFilename=C:\\Users\\Administrator\\Documents\\Contact.mdf;Integrated Security=True;");
    SqlDataAdapter da = new SqlDataAdapter();
    DataSet ds = new DataSet();
    public Form2()
    {
        InitializeComponent();            
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        bindDatagridview();  
        if (textBox1.Text != string.Empty)      
        {      
            search();            
        }
    }
    public void bindDatagridview()
    {
        SqlDataAdapter da = new SqlDataAdapter();
        DataSet ds = new DataSet();
        da.SelectCommand = new SqlCommand("Select * from contactsinfo", connection);
        da.Fill(ds);
        dataGridView1.DataSource = ds.Tables[0];
        //dataGridView1.DataBindings();
    }
    public void search()
    {
        da.SelectCommand = new SqlCommand("Select * from contactsinfo where ContactName = '" + textBox1.Text + "'", connection);
        da.Fill(ds);
        dataGridView1.DataSource = ds.Tables[0];
        clear();
    }
}

But this only work when the form is load and the form is only loaded at first time: Kindly suggest me what i do, waiting for your reply. Thanks.

Answer 1

If you can load all contacts at once, then its simple. On form load get all contacts and save them in DataView. Then bind grid to this view:

DataView contactsView;

private void Form2_Load(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        var da = new SqlDataAdapter("SELECT * FROM from contactsinfo", conn);
        da.Fill(dt);
    }

    contactsView = dt.AsDataView();
    dataGridView1.DataSource = contactsView;    
}

Then just change row filter of DataView when text changes in filter TextBox:

private void textBox1_TextChanged(object sender, EventArgs e)
{
    contactsView.RowFilter = 
       String.Format("ContactName LIKE '{0}%'", textBox1.Text);
}

If you can't pre-load all data, then you should use same TextChanged event to query for filtered data.

NOTE: You should handle ' in user input.