mysql - UPDATE Same Row After UPDATE in Trigger -

i want epc column earnings/clicks. using after update trigger accomplish this. if add 100 clicks table, want epc update automatically.

i trying this:

create trigger `records_integrity` after update on `records` each row set  new.epc=ifnull(earnings/clicks,0); 

and getting error:

mysql said: #1362 - updating of new row not allowed in after trigger 

i tried using old got error. before if added 100 clicks use previous # clicks trigger (right?)

what should accomplish this?

edit - example of query run on this:

update records set clicks=clicks+100 //epc should update automatically 

you can't update rows in table in after update trigger.

perhaps want this:

create trigger `records_integrity` before update on `records` each row     set new.epc=ifnull(new.earnings/new.clicks, 0); 

edit:

inside trigger, have have access old , new. old old values in record , new new values. in before trigger, new values written table, can modify them. in after trigger, new values have been written, cannot modified. think mysql documentation explains pretty well.