主类java.sql.SQLException中的异常：超出锁定等待超时;尝试重新启动事务

Question

执行java程序时出现以下错误

 Exception in main class java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction

程序：

    String query = "select id from testtable where status=\"" + 1 + "\" limit 10";
                    PreparedStatement s = conn.prepareStatement(query);
                    ResultSet res = s.executeQuery();

                   while (res.next()) {

                        CId = res.getString(1);
                        System.out.println("cid:"+CId);

               String delquery = "delete from testtable2 where comid=\"" + CId + "\"";
                    PreparedStatement pre = conn.prepareStatement(delquery);
                    System.out.println("del:"+pre.executeUpdate());

            String delquery2 = "delete from testtable where id=\"" + CId + "\"";
                    PreparedStatement pre2 = conn.prepareStatement(delquery2);
                    pre2.executeUpdate();
}