MySQL Unknown Column Error 1054 Simple Update -

using mysql workbench, i'm getting odd behavior when attempting execute following statement:

update jobs set customer = 'ben' po = 1011; 

the output of is: error code: 1054. unknown column 'jobs.po' in 'where clause'

the goal here update statement, or equivalent, execute. can't determine issue. what's particularly odd following statements:

select * jobs; select po jobs; select * jobs po = 1011; select po jobs po = 1011; 

all function expected. specifically, no errors, returns , displays entries asked for. why might select execute without 1054 error when update can't?

the create table statement (if it's helpful), executed sql script through workbench:

create table `jobs` (     po mediumint not null,     part tinyint unsigned not null default 1,     `last dash` smallint unsigned not null default 0,     customer varchar(80),     description varchar(350),     completed date,     notes varchar(350),     constraint pkjobs primary key (po, part) ); 

edit:: perhaps not simple construed. there exists 'before update' trigger on table.

delimiter // drop trigger if exists jobsup // create trigger jobsup before update on jobs each row begin      if new.`last dash` < (select max(dash)          tracking t          new.po = t.po          , new.part = t.part      )           signal sqlstate '45000' set message_text =              'cannot update last dash value less assigned dash.';       end if;  end // delimiter ; 

figured out. database operating previous definition of jobsup trigger did not utilize 'new' keyword. recreating trigger solved issue.