Save Checked ( Selected ) Rows from GridView with CheckBoxes to Database in ASP.Net

For Check All Checkboxes you need to refer Implement check all checkbox functionality in ASP.Net GridView control using JavaScript

Html Code

  <div>
        <asp:GridView ID="gvEmployees" runat="server" AutoGenerateColumns="false">
            <Columns>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:CheckBox ID="chkEmployee" runat="server" AutoPostBack="true" OnCheckedChanged="SaveEmployees" />
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:TextBox ID="txtEmpId" runat="server" Text='<%#Eval("empid")%>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:TextBox ID="txtEmpName" runat="server" Text='<%#Eval("empname")%>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:TextBox ID="txtCompName" runat="server" Text='<%#Eval("compname")%>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
    </div>

Code

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            gvEmployees.DataSource = this.GetData();
            gvEmployees.DataBind();
        }
    }

    private DataTable GetData()
    {
        string connection = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        using (SqlConnection con = new SqlConnection(connection))
        {
            using (SqlCommand cmd = new SqlCommand("SELECT * FROM Employees_1", con))
            {
                using (SqlDataAdapter da = new SqlDataAdapter())
                {
                    da.SelectCommand = cmd;
                    using (DataTable dt = new DataTable())
                    {
                        da.Fill(dt);
                        return dt;
                    }
                }
            }
        }
    }
   
    protected void SaveEmployees(object sender, EventArgs e)
    {
        foreach (GridViewRow row in gvEmployees.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                CheckBox chkEmployee = (CheckBox)row.FindControl("chkEmployee");
                if (chkEmployee.Checked)
                {
                    TextBox txtEmpId = (TextBox)row.FindControl("txtEmpId");
                    TextBox txtEmpName = (TextBox)row.FindControl("txtEmpName");
                    TextBox txtCompName = (TextBox)row.FindControl("txtCompName");
                    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conSTring"].ConnectionString))
                    {
                        using (SqlCommand cmd = new SqlCommand("INSERT INTO Employees_2 VALUES(@empid,@empname,@compname)", con))
                        {
                            cmd.Parameters.AddWithValue("@empid", txtEmpId.Text.Trim());
                            cmd.Parameters.AddWithValue("@empname", txtEmpName.Text.Trim());
                            cmd.Parameters.AddWithValue("@compname", txtCompName.Text.Trim());
                            con.Open();
                            cmd.ExecuteNonQuery();
                            con.Close();
                        }
                    }
                }
            }
        }
    }

Namespaces

using System;
using System.Web.UI.WebControls;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;