foreach (GridViewRow row in USER_GROUP_FROMS.Rows)
{
    var chkboxuser = (CheckBox)row.FindControl("mainsupp");

    abc = "";

    if (chkboxuser.Checked == true)
    {
        string xe = "DATA SOURCE=technovalms;USER ID=AMC; password=amc;";
        OracleConnection conn = new OracleConnection();
        conn.ConnectionString = xe;

        OracleCommand cmd = new OracleCommand();
        cmd.Connection = conn;

        conn.Open();

        cmd.CommandText = "insert into TECHNOVA_SMS_USER_PRIVILEAGE(ID,SMS_USER_ID,SMS_PAGE_ID) values(SEQUENCEMODEL.nextval,'" + user_type.SelectedValue.ToString() + "','" + chkboxuser + "') ";

        cmd.ExecuteNonQuery();
    }
}

1';DELETE FROM TECHNOVA_SMS_USER_PRIVILEAGE'

cmd.CommandText = "insert into TECHNOVA_SMS_USER_PRIVILEAGE(ID,SMS_USER_ID,SMS_PAGE_ID) values(SEQUENCEMODEL.nextval,':selectedValue',':chkboxuser') ";

cmd.Parameters.Add(new OracleParameter("selectedValue", user_type.SelectedValue.ToString()));
cmd.Parameters.Add(new OracleParameter("chkboxuser", chkboxuser));