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I have this table

CREATE table Pharmacists (
PhFname varchar2(10),
PhLname varchar2(10),
Salary number(7),
Nationality varchar2(10),
Shift_Start varchar2(2),
Shift_End varchar2(2),
PhID number(7) primary key,
Super_ID number(7) ,
bdate date,
constraint super_fk foreign key (Super_ID) references Pharmacists (PhID) on delete cascade);

I tried to create this trigger

create or replace trigger updShE
after update of Shift_Start on Pharmacists
begin
update Pharmacists
set Shift_End=to_number(:new.Shift_Start, '99') +8 
where PhID = :New.PhID ;
end;

but this error appears

new or old reference not allowed in table level trigger

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  • 1
    Unrelated, but: I would store shift_start and shift_end (which seems to be a time of day information) as a number to make calculations easier. E.g. minutes since midnight or just "hours" if you don't need minutes. Storing numbers in varchar columns is usually a bad idea – a_horse_with_no_name Dec 8 '17 at 7:37
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You need a row before level trigger for that.

And you don't need an update, just assign the new value:

create or replace trigger updshe
  BEFORE update of Shift_Start on Pharmacists
  FOR EACH ROW
begin
  :new.shift_end := to_number(:new.Shift_Start, '99') + 8;
end;
/
3
  • error can't change new values for this trigger type – Rand alrand Dec 8 '17 at 7:46
  • @Randalrand: ah sorry, I overlooked that you are using an after trigger. You obviously need a BEFORE trigger for that – a_horse_with_no_name Dec 8 '17 at 7:49
  • thank you it's working now but why before not after? why should we not use update? – Rand alrand Dec 8 '17 at 8:25

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