How to execute host command in trigger

Question

dear professional:
i'm trying to create a trigger that when a certain value inserts into a table , it fires some UNIX command to do the job following
here is what i tried ,create a trigger that gives host command , but when i tried insert , it fails to work
i also tried dbms_pipe ,but seems same when using dynamic sql to do the job
any idea of how to accomplish this task ?
many thanks ~
br/ricky
SQL> CREATE OR REPLACE TRIGGER price_exec
2 BEFORE INSERT ON omc.price_test
FOR EACH ROW
BEGIN
IF :NEW.price = 4 THEN
execute immediate 'host ll';
END IF;
END price_exec;
/ 3 4 5 6 7 8 9
Trigger created.
SQL> insert into price values ('test',4);
insert into price values ('test',4)
ERROR at line 1:
ORA-00942: table or view does not exist
SQL> insert into price_test values ('test',4);
insert into price_test values ('test',4)
ERROR at line 1:
ORA-00900: invalid SQL statement
ORA-06512: at "OMC.PRICE_EXEC", line 3
ORA-04088: error during execution of trigger 'OMC.PRICE_EXEC'

Answer 1

hi,
my db is 9.2
i'm aware of schedule you mentioned , but if it's up to the task , you don't know when a row with certain value is inserted
simple way :
when a row inserted into a table with value "catch me" you want to know who inserted this test value
so you tried to create a trigger to catch program, machine, module ,and terminal info from v$session
so you can figure out where it is coming from
and i want to go a step further , by executing some os command to digging out more
and i come up with this , when value 4 is inserted i exec a procedure host to execute command,
the problem is it's not working as i exepcted , so spare me the lecture of reading docs and just tell me what to do
i'd really appreciate it , thanks
CREATE OR REPLACE TRIGGER price_exec
BEFORE INSERT ON omc.price_test
FOR EACH ROW
BEGIN
IF :NEW.price = 4 THEN
execute immediate 'host('echo')';
END IF;
END;
Warning: Trigger created with compilation errors.
SQL> show errors
Errors for TRIGGER PRICE_EXEC:
LINE/COL ERROR
3/30 PLS-00103: Encountered the symbol "ECHO" when expecting one of
the following:
. ( * @ % & = - + ; < / > at in is mod not rem return
returning <an exponent (**)> <> or != or ~= >= <= <> and or
like between into using || bulk
The symbol ". was inserted before "ECHO" to continue.