Update record in database from TextBox

HI makenzi.exc,

Please refer the below sample.

Database

CREATE TABLE [dbo].[Vegitables](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[Name] [varchar](50) NULL,
	[PricePerkg] [int] NULL,
	[QtyInKg] [int] NULL,
 CONSTRAINT [PK_Vegitables] PRIMARY KEY CLUSTERED 
(
	[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

HTML

<asp:GridView ID="gvVegitables" runat="server" AutoGenerateColumns="false" OnSelectedIndexChanged="OnSelectedIndexChanged">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="PricePerKg" HeaderText="PricePerKg" />
        <asp:BoundField DataField="QtyInKg" HeaderText="QtyInKg" />
        <asp:ButtonField Text="Select" CommandName="Select" />
    </Columns>
</asp:GridView>
<br />
<br />
<table>
    <tr>
        <td>Id:</td>
        <td>
            <asp:Label ID="lblId" runat="server"></asp:Label></td>
    </tr>
    <tr>
        <td>Name:</td>
        <td>
            <asp:TextBox ID="txtName" runat="server"></asp:TextBox></td>
    </tr>
    <tr>
        <td>PricePerKg</td>
        <td>
            <asp:TextBox ID="txtPricePerKg" runat="server"></asp:TextBox></td>
    </tr>
    <tr>
        <td>QtyInKg</td>
        <td>
            <asp:TextBox ID="txtQtyInKg" runat="server"></asp:TextBox></td>
    </tr>
    <tr>
        <td></td>
        <td>
            <asp:Button runat="server" Text="Update" OnClick="OnUpdate" /></td>
    </tr>
</table>

Namespaces

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

code

#region Events

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}

protected void OnUpdate(Object sender, EventArgs e)
{
    //Reading the values.
    int id = int.Parse(lblId.Text);
    string name = txtName.Text.Trim();
    int pricePerKg = int.Parse(txtPricePerKg.Text);
    int qtyInKg = int.Parse(txtQtyInKg.Text);
    int rowaAffected = 0;

    //Sql query store in variable.
    string query = "UPDATE Vegitables SET  Name = @Name, PricePerKg = @PricePerKg, QtyInKg = @QtyInKg WHERE  Id = @Id";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

    //Creating sql connection.
    using (SqlConnection sqlConnection = new SqlConnection(constr))
    {
        using (SqlCommand sqlCommand = new SqlCommand(query, sqlConnection))
        {
            //Passing the parameters with the values.
            sqlCommand.Parameters.AddWithValue("@Id", id);
            sqlCommand.Parameters.AddWithValue("@Name", name);
            sqlCommand.Parameters.AddWithValue("@PricePerKg", pricePerKg);
            sqlCommand.Parameters.AddWithValue("@QtyInKg", qtyInKg);

            //Opening the sql connection .
            sqlConnection.Open();

            //Executing the sql query.
            rowaAffected = sqlCommand.ExecuteNonQuery();

            //Closing the sql connection.
            sqlConnection.Close();
        }
    }
    this.BindGrid();
}

protected void OnSelectedIndexChanged(object sender, EventArgs e)
{       
    int id = int.Parse(gvVegitables.SelectedRow.Cells[0].Text);
    string name = gvVegitables.SelectedRow.Cells[1].Text;
    int pricePerKg = int.Parse(gvVegitables.SelectedRow.Cells[2].Text);
    int qtyInKg = int.Parse(gvVegitables.SelectedRow.Cells[3].Text);
    lblId.Text = id.ToString();
    txtName.Text = name;
    txtPricePerKg.Text = pricePerKg.ToString();
    txtQtyInKg.Text = qtyInKg.ToString();
}

#endregion

#region Private Methods

/// <summary>
/// Populates GridView
/// </summary>
private void BindGrid()
{
    String constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection sqlConnection = new SqlConnection(constr))
    {
        using (SqlCommand sqlCommand = new SqlCommand("SELECT * FrOM Vegitables", sqlConnection))
        {
            using (SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand))
            {
                using (DataTable dtVegetables = new DataTable())
                {
                    sqlDataAdapter.Fill(dtVegetables);
                    gvVegitables.DataSource = dtVegetables;
                    gvVegitables.DataBind();
                }
            }
        }
    }
}

#endregion

Screenshot