Simple Search Functionality

Firstly In aspx page add textbox,Butoon to search and grid view to display records.

 <asp:TextBox ID="txtSEarch" runat="server"></asp:TextBox>
    <asp:Button ID="btnSerach" runat="server" Text="Search" OnClick="SearchData" />
    <asp:GridView ID="GridView1" runat="server"></asp:GridView>

In Code Behind:
Name spaces Used are:

using System.Configuration;
using System.Data.SqlClient;
using System.Data;

 string _connstr = ConfigurationManager.ConnectionStrings["Connstr"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void SearchData(object sender, EventArgs e)
    {
        DataTable table = new DataTable();
       
        using (SqlConnection conn = new SqlConnection(_connstr))
        {
            string SQL = "SELECT * FROM PersonDetails2 WHERE FirstName like '%" + (txtSEarch.Text) + "%'";
            using (SqlCommand cmd = new SqlCommand(SQL, conn))
            {
                conn.Open();

                cmd.ExecuteNonQuery();
                SqlDataAdapter da = new SqlDataAdapter();
                da.SelectCommand = cmd;
                DataSet ds = new DataSet();
                da.Fill(ds, "PersonDetails2");
                GridView1.DataSource = ds;
                GridView1.DataBind();
                conn.Close(); 
            }
            
        }
    }

Thanks & Regards