Trigger for multile fields in same table.

Question

--thanks in advance,
--I need help to write a trigger .
-- this is what i wanted
CREATE OR REPLACE TRIGGER Chk_Uniq_Qtr -- trigger name
Before insert or Update on Pro_well_Calender -- tbl name
for each row
Declare
N_Qtr1 varchar2(2);
N_Qtr2 varchar2(2);
N_Qtr3 varchar2(2);
N_Qtr4 varchar2(2);
Begin
N_Qtr1 := upper(Pro_well_Calender.Quarter1); -- column name
N_Qtr2 := upper(Pro_well_Calender.Quarter2);
N_Qtr3 := upper(Pro_well_Calender.Quarter3);
N_Qtr4 := upper(Pro_well_Calender.Quarter4);
-- But the only valid values for Quarter1 is 'April','May','June');
-- But the only valid values for Quarter2 is 'july','Auguest','September');
-- But the only valid values for Quarter1 is 'October','November','December');
-- But the only valid values for Quarter1 is 'January','February',March');
-- I need to check
IF N_Qtr1 is not in ('April','May','June') then
raise_error('Enter a month for Quarter 1'); end if;
IF N_Qtr2 is not in ('july','Auguest','September') then
raise_error('Enter a month for Quarter 2'); end if;
IF N_Qtr3 is not in ('October','November','December') then
raise_error('Enter a month for Quarter 3'); end if;
IF N_Qtr4 is not in ('January','February',March') then
raise_error('Enter a month for Quarter 4');end if;
end trigger.
--I did what ever i can but none worked.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Answer 1

Hi,
It looks like you're on the right track.
If the local varibales
N_Qtr1 varchar2(2);
N_Qtr2 varchar2(2);
N_Qtr3 varchar2(2);
N_Qtr4 varchar2(2);
Begin
N_Qtr1 := upper(Pro_well_Calender.Quarter1); -- column name
N_Qtr2 := upper(Pro_well_Calender.Quarter2);
N_Qtr3 := upper(Pro_well_Calender.Quarter3);
N_Qtr4 := upper(Pro_well_Calender.Quarter4);are only 2 characters long, they will never be equal to 'April', 'May' or 'June'.
Also, if they are the values retruned by UPPER, they will never contain lower-case letters like 'p', 'r', 'i' or 'l'.
You probably meant to say :NEW instead of pro_well_calendar in the code above.
To raise an user-defined or pre-defined (built-in) error, use RAISE.
Instead of defining an error, you can use RAISE_APPLICATION_ERROR, like this
RAISE_APPLICATION_ERROR (-20012, 'Invalid quarter');Don't write so much code at once. Take baby steps.
For example, code, test, and debug the code for the quarter1 column first.
When that is working perfectly, you can copy it to handle the other 3 columns.