Grid View Assignment -01 [Attendence]

 Q. Insert checkbox and textbox in grid view and create a column in data base table named "Attendence" when a user Select the record using checkbox and input present/absent in textbox should be reflected to the database table.

Update Selection(button) 

Code- 

{

        string s = @"Data Source=49.50.88.43;Initial Catalog=grkistdb;Persist Security Info=True;User ID=grkistuser;Password=q2oR5w_356";

        cn = new SqlConnection(s);

        cn.Open();

        foreach (GridViewRow gr1 in GridView1.Rows)

        {

            CheckBox c1 = (CheckBox) gr1.FindControl("cb1");

            TextBox t1 = (TextBox)gr1.FindControl("tb1");

            if (c1.Checked)

            {

                

                string q = "update Chitransh_reg set Attendance ='" + t1.Text + "' where roll='"+gr1.Cells[1].Text+"'";

  

                cm = new SqlCommand(q, cn);

                

                cm.ExecuteNonQuery();

            } 

        }

    }