Printing a statement in stored procedure - oracle

Question

I have written some code to print whether the condition is true/false, but I can't get the output as true / false. Why?
Here is that code:
create or replace PROCEDURE TET_STOP_DID
IS
result VARCHAR2(10);
LastGeneratedcode TET_LASTGENERATEDMASKCODE.Maskedcode%TYPE;
BEGIN
select maskedcode into LastGeneratedcode from TET_LASTGENERATEDMASKCODE;
IF (SUBSTR(LastGeneratedcode,5,5) !='ZZZZZ') then
result := 'true';
else
result :='false';
END IF;
END TET_STOP_DID;

Answer 1

You aren't printing anything; you've just set the result variable to some value, and that's it. Though, that procedure doesn't look right as it'll raise too_many_rows error if there are two (or more) rows in the table (or no_data_found if it is empty). I presume you'd want to pass some parameter which restricts number of fetched rows.
For example:
SQL> select * from tet_lastgeneratedmaskcode;
ID MASK
---------- ----
1 abcd
2 fff
Procedure which accepts a parameter and handles exceptions (that's rather poor handling, just to show what to pay attention to):
SQL> create or replace procedure tet_stop_did
2 (par_id in tet_lastgeneratedmaskcode.id%type)
3 is
4 result varchar2(10);
5 lastgeneratedcode tet_lastgeneratedmaskcode.maskedcode%type;
6 begin
7 select maskedcode
8 into lastgeneratedcode
9 from tet_lastgeneratedmaskcode
10 where id = par_id;
11
12 if substr(lastgeneratedcode, 5, 5) != 'ZZZZZ' then
13 result := 'true';
14 else
15 result := 'false';
16 end if;
17
18 dbms_output.put_line('Result = ' || result);
19 exception
20 when no_data_found then
21 dbms_output.put_line('No rows for that ID');
22 when too_many_rows then
23 dbms_output.put_line('Two or more rows for that ID');
24 end tet_stop_did;
25 /
Procedure created.
Testing:
SQL> set serveroutput on
SQL> exec tet_stop_did (1);
Result = false --> here's your result
PL/SQL procedure successfully completed.
SQL>

Answer 2

If you can use SERVEROUTPUT clause to run the procedure you may insert DBMS_OUTPUT in stored procedure code:
CREATE OR REPLACE PROCEDURE TET_STOP_DID
IS
result VARCHAR2(10);
LastGeneratedcode TET_LASTGENERATEDMASKCODE.Maskedcode%TYPE;
BEGIN
select maskedcode into LastGeneratedcode from TET_LASTGENERATEDMASKCODE;
IF (SUBSTR(LastGeneratedcode,5,5) !='ZZZZZ') then
result := 'true';
ELSE
result := 'false';
END IF;
-- Print the output
DBMS_OUTPUT.PUT_LINE(result);
END TET_STOP_DID;
And then from terminal, it runs so:
SQL> SET SERVEROUTPUT ON;
SQL> EXECUTE TET_STOP_DID
false
Thank you