SQL developer: How to make log output from a trigger? - oracle

Question

I've made a trigger in SQL and need him to write an output after inserting a new row in the table. Please see the example:
CREATE OR REPLACE TRIGGER GAS_CODES AFTER
INSERT ON blablatable
FOR EACH ROW
BEGIN
insert into blabla2table (...,...,...,...)
values (:new...,...,...,..);
---output:
dbms_output.put_line('New row has been added.');
END;
/
When I compile the trigger, it shows in the Script Output, but if I add a new row into the table, there's nothing.

Answer 1

You are missing SET SERVEROUTPUT ON. This command is understandable also by SQLDeveloper.
Let's do a quick test inside the SQLDeveloper.
CREATE USER "TEST_SCHEMA" IDENTIFIED BY "TEST";
User "TEST_SCHEMA" created.
GRANT UNLIMITED TABLESPACE TO "TEST_SCHEMA";
Grant succeeded.
CREATE TABLE "TEST_SCHEMA"."NAMES" ("ID" NUMBER, "NAME" VARCHAR2(25), PRIMARY KEY("ID"));
Table "TEST_SCHEMA"."NAMES" created.
CREATE OR REPLACE TRIGGER "TEST_SCHEMA"."NAMES_TRG_1" AFTER
INSERT ON "TEST_SCHEMA"."NAMES"
FOR EACH ROW
BEGIN
DBMS_OUTPUT.PUT_LINE('New row has been added.');
END;
/
Trigger NAMES_TRG_1 compiled
SET SERVEROUTPUT ON
This command won't print anything in SQL Developer. No worries here.
INSERT INTO "TEST_SCHEMA"."NAMES" VALUES (1, 'Mark Smith');
1 row inserted.
New row has been added.
As you can see, the output was there and it was inserted after the actual row was inserted into the table. Works fine.
To cleanup the testcase, run this:
DROP USER "TEST_SCHEMA" CASCADE;
EDIT 1:
When you are working with Table Data Editor, this is behaving differently. Table Data Editor has its own Oracle session and it has different way of capturing DBMS Output.
To open the DBMS capture window, you need to click on "VIEW" menu and select "DBMS Output" option.
Then click the green plus button and set the database, that will be captured.
Now you can see the output.
Beware as the output here is not "realtime", this window will show something only when there is a buffer flush, and the buffer flush cannot be invoked manually/directly.

Answer 2

Most likely the client (SQLDeveloper) doesn't read the output buffer.
To enable this you must choose from menu "view" -> "dbms output" and then click the green "+" in the dbms output window to read the output buffer for your connection ...
In sqlplus you can do it like this:
SQL> drop table tst purge;
Table dropped.
SQL> drop table tst2 purge;
Table dropped.
SQL> create table tst ( tst_no integer);
Table created.
SQL> create table tst2 ( tst_no integer);
Table created.
SQL> create or replace trigger tst_trg after insert on tst
for each row
begin
insert into tst2 (tst_no) values (:new.tst_no);
dbms_output.put_line('new row with tst_no='|| :new.tst_no);
end;
/ 2 3 4 5 6 7
Trigger created.
SQL> set serveroutput on;
exec dbms_output.enable;
insert into tst values (1); SQL>
PL/SQL procedure successfully completed.
SQL> SQL>
new row with tst_no=1
1 row created.
SQL> r
1* insert into tst values (1)
new row with tst_no=1
1 row created.
SQL> select * from tst2;
TST_NO
----------
1
1
SQL>
as you can see the output is read and printed in sqlplus, and rows are inserted into the target table tst2
hope it helps...