Asp.net Gridview edit update and delete code

In GridViewEditUpdateDelete.aspx add the following code ( in the form tag )

<asp:GridView ID="gvPatients" AutoGenerateColumns="false" runat="server"
    AutoGenerateEditButton="true" AutoGenerateDeleteButton="true"
    DataKeyNames="PatientID"
        onrowediting="gvPatients_RowEditing"
        OnRowCancelingEdit="gvPatients_RowCancel" OnRowUpdating="gvPatients_RowUpdating"
        OnRowDeleting="gvPatients_RowDeleting"
        onselectedindexchanged="gvPatients_SelectedIndexChanged">
    <HeaderStyle BackColor="AliceBlue" ForeColor="Red"/>
    <Columns>
    <asp:TemplateField HeaderText="PatientID">
    <ItemTemplate>
    <asp:Label ID="lblPatientID" runat="server" Text='<%#Eval("PatientID") %>'/>
    </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="PatientName">
    <EditItemTemplate>
    <asp:TextBox ID="tbName" runat="server" Text='<%#Eval("PatientName")%>' />
    </EditItemTemplate>
    <ItemTemplate>
    <asp:Label ID="lblName" runat="server" Text='<%#DataBinder.Eval(Container.DataItem,"PatientName")%>' />
    </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="AGE">
    <EditItemTemplate>
    <asp:TextBox ID="tbAge" runat="server" Text='<%#Eval("age")%>' />
    </EditItemTemplate>
    <ItemTemplate>
    <asp:Label ID="lblAge" runat="server" Text='<%#Eval("age")%>' />
    </ItemTemplate>
    </asp:TemplateField>  
    </Columns>
    </asp:GridView>

In .aspx.cs page add the following code:

public partial class DataGridColumns : System.Web.UI.Page

{

    DataSet ds = new DataSet();

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            FillPatientInfo();

        }

    }

    private void FillPatientInfo()

    {

        //bad approach for getting connection string.

        string strcon = "data source=your sql server name ;initial catalog=your database name ;integrated security=sspi";

        SqlConnection cn = new SqlConnection(strcon);

        SqlCommand cmd = new SqlCommand("select * from patient", cn);

        SqlDataAdapter da = new SqlDataAdapter();

        da.SelectCommand = cmd;

        da.Fill(ds);

        gvPatients.DataSource = ds;

        gvPatients.DataBind();

        Session["dsPatients"] = ds;

        //GridView1.DataSource = ds;

        //GridView1.DataBind();

    }

    protected void gvPatients_RowEditing(object sender, GridViewEditEventArgs e)

    {

        gvPatients.EditIndex = e.NewEditIndex;

        gvPatients.DataSource = (DataSet)Session["dsPatients"];

        gvPatients.DataBind();

    }

    protected void gvPatients_RowDeleting(object sender, GridViewDeleteEventArgs e)

    {

        Label lblPatientID = (Label)gvPatients.Rows[e.RowIndex].FindControl("lblPatientID");

        SqlConnection cn = new SqlConnection("data source=ADMIN-PC\\SQLEXPRESS;initial catalog=palletechnologies;integrated security=sspi");

        SqlCommand cmd = new SqlCommand();

        StringBuilder sb = new StringBuilder();

        sb.Append("delete patient where patientid='" + lblPatientID.Text + "'");

        cmd.CommandText = sb.ToString();

        cmd.Connection = cn;

        cn.Open();

        cmd.ExecuteNonQuery();

        cn.Close();

        FillPatientInfo();

    }

    protected void gvPatients_RowUpdating(object sender, GridViewUpdateEventArgs e)

    {

        Label lblPatientID = (Label)gvPatients.Rows[e.RowIndex].FindControl("lblPatientID");

        TextBox tbAge = (TextBox)gvPatients.Rows[e.RowIndex].FindControl("tbAge");

        TextBox tbName = (TextBox)gvPatients.Rows[e.RowIndex].FindControl("tbName");

        SqlConnection cn = new SqlConnection("data source=ADMIN-PC\\SQLEXPRESS;initial catalog=palletechnologies;integrated security=sspi");

        SqlCommand cmd = new SqlCommand();

        StringBuilder sb = new StringBuilder();

        sb.Append("update patient set patientname='" + tbName .Text+ "',");

        sb.Append("age='"+tbAge.Text+"' where patientid='"+lblPatientID.Text+"'");

        cmd.CommandText = sb.ToString();

        cmd.Connection = cn;

        cn.Open();

        cmd.ExecuteNonQuery();

        cn.Close();

        gvPatients.EditIndex = -1;

        FillPatientInfo();

    }

    protected void gvPatients_SelectedIndexChanged(object sender, EventArgs e)

    {

        

    }

    protected void gvPatients_RowCancel(object sender, GridViewCancelEditEventArgs e)

    {

        gvPatients.EditIndex = -1;

        e.Cancel = true;

        gvPatients.DataSource = (DataSet)Session["dsPatients"];

        gvPatients.DataBind();

    }

}

Patient table structure: 

Create a patient table with PatientID,PatientName and Age columns.