FILTER GRIDVIEW WITH TEXTBOX IN C# ASP.NET

you need to add this code in the .aspx page

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<asp:Button ID="btnSearch" runat="server" Text="Click Me!"
onclick="btnSearch_Click" />



and you need to add this code in .aspx.cs page

protected void btnSearch_Click(object sender, EventArgs e)
{
SqlConnection sqlcon = new SqlConnection(connstring);
string str = txtSearch.Text;
SqlCommand sqlcmd = new SqlCommand("select * from [table name] where fieldname like '%" + str + "%'", sqlcon);
SqlDataAdapter adp = new SqlDataAdapter(sqlcmd);
DataSet ds = new DataSet();
adp.Fill(ds);
if (ds.Tables[0].Rows.Count > 0)
{
lbl1.Visible = false;
gvActivities.DataSource = ds.Tables[0];
gvActivities.DataBind();
}
else
{
lbl1.Visible = true;
}
}