Exception in procedure - oracle

Question

I have procedure like below, but when block is run it does not shows message for error if data is not found.
CREATE OR REPLACE
PROCEDURE DDPROJ_SP
(P_IDPROJ IN DD_PROJECT.IDPROJ%TYPE,
P_INFO OUT VARCHAR2,
p_check OUT VARCHAR2)
IS
CURSOR cur_ddproj IS
SELECT *
FROM dd_project
WHERE idproj = p_idproj;
lv_projinfo_txt VARCHAR2(100);
BEGIN
FOR rec_ddproj IN cur_ddproj LOOP
lv_projinfo_txt := (rec_ddproj.idproj||', '||rec_ddproj.projname||
', '||rec_ddproj.projstartdate||', '||rec_ddproj. projenddate||
', '||rec_ddproj.projfundgoal||', '||rec_ddproj.p rojcoord);
END LOOP;
P_INFO := LV_PROJINFO_TXT;
EXCEPTION
WHEN NO_DATA_FOUND THEN
P_CHECK :='Please select another project';
DBMS_OUTPUT.PUT_LINE(P_CHECK);
END;
And block:
DECLARE
LV_INFO_TXT VARCHAR2(100);
LV_CHECK_TXT VARCHAR2(30);
BEGIN
DDPROJ_SP(00,lv_info_txt,lv_check_txt);
DBMS_OUTPUT.PUT_LINE(LV_INFO_TXT);
END;
After RUNNING BLOCK IF id provided is correct I would receive requested information but if ID is not found exception will not show message on print.

Answer 1

Firstly, as has been pointed out, your exception handler doesn't do anything really visible except call dbms_output, the results of which you'll only see if you set serverout on or otherwise access the results from dbms_output.
Secondly and more importantly, when you use a FOR loop to process the results of a cursor, the NO_DATA_FOUND exception will never be raised.
If you want to detect no rows found, you have a few options:
After the loop, check if the variable was set, e.g.:
...
end loop;
if lv_projinfo_txt is null then
raise no_data_found;
end if;
If you don't expect more than 1 record to be found by the query (which is suggested by your predicate on an "id"), you can avoid the FOR loop and use a simple select into:
PROCEDURE DDPROJ_SP
(P_IDPROJ IN DD_PROJECT.IDPROJ%TYPE,
P_INFO OUT VARCHAR2,
p_check OUT VARCHAR2)
IS
rec_ddproj dd_project%rowtype;
lv_projinfo_txt VARCHAR2(100);
BEGIN
SELECT *
into rec_ddproj
FROM dd_project
WHERE idproj = p_idproj;
lv_projinfo_txt := (rec_ddproj.idproj||', '||rec_ddproj.projname||
', '||rec_ddproj.projstartdate||', '||rec_ddproj.projenddate||
', '||rec_ddproj.projfundgoal||', '||rec_ddproj.projcoord);
P_INFO := LV_PROJINFO_TXT;
EXCEPTION
WHEN NO_DATA_FOUND THEN
P_CHECK :='Please select another project';
DBMS_OUTPUT.PUT_LINE(P_CHECK);
END;
Notes:
A select into may raise NO_DATA_FOUND or TOO_MANY_ROWS.
Good practice is to never handle errors without re-raising the exception, unless your code actually handles the exception. In your case, your code merely sends a signal back to the calling process via the p_check parameter, which moves responsibility for handling the error to the caller. This might be ok in some circumstances but it assumes the caller actually heeds the signal. It would be better to raise an exception which forces the caller to handle it appropriately.
Good practice is to alias all columns and parameters in a query; having a SQL predicate like idproj = p_idproj makes the assumption that the table will never have a column called p_idproj in the future. Instead, it's good practice to deliberately alias all columns and parameters, e.g.
SELECT x.*
into rec_ddproj
FROM dd_project x
WHERE x.idproj = ddproj_sp.p_idproj;