try.sql

create table mass_email_recipients (
    id integer,
    mass_email_send_id integer,
    status integer
);

insert into mass_email_recipients
values (240, 154, 1),
       (241, 154, 1),
       (241, 154, 0);

begin;

select id from mass_email_recipients
 where mass_email_send_id = 154 and status = 1;

update mass_email_recipients set status = 2 where id in (
    select id from mass_email_recipients
     where mass_email_send_id = 154 and status = 1
);

rollback;

BEGIN;

update mass_email_recipients set status = 2
 where mass_email_send_id = 154 and status = 1;

ROLLBACK;

drop table mass_email_recipients;