If no data then don't create empty file - oracle

Question

I would like to check if there's no data coming from SQL query then file should not be created.
Here is my code:
CREATE OR REPLACE PROCEDURE VR_AD_INTEGRATION_EXPORT AS
l_v_file UTL_FILE.file_type
BEGIN
l_v_file := UTL_FILE.fopen('integration', 'HRMtoAD1_'||to_char(sysdate,'YYYYMMDD')||'_'||to_char(sysdate,'HH24MISS'), 'w', 32767);
FOR x IN (SELECT * FROM (SELECT
decode(pid, NULL, RPAD(' ',7,' '), RPAD(user_id, 7, ' '))|| '' ||
decode(name_last, NULL, RPAD(' ',50,' '), RPAD(name_last, 50, ' '))
str FROM vr_ad_integration WHERE integrated = 'N') str WHERE rownum <= 1000 ORDER BY rownum)
LOOP
BEGIN
UTL_FILE.put_line(l_v_file, x.str);
END;
END LOOP;
UTL_FILE.fflush(l_v_file);
UTL_FILE.fclose(l_v_file);
END VR_AD_INTEGRATION_EXPORT;
Now I can create file successfully in a remote location. However, what if there's no data in select query? no file should be created. If I am correct, I need to include exception code but I have no idea how to do it in this case. Any suggestion?
Cheers! :-)

Answer 1

There are several ways to achieve this. One is to adopt a more procedural approach with a explicit cursor and only open the file once a record is fetched. A second is to modify your code to include a count inside the loop and delete the file if the count is zero.
Here is a third choice, which is a variant on the previous option. It tests the size of the file and if it is zero deleted it using the UTL_FILE.FREMOVE() command. Note the need to store the generated file name in a variable for reference later.
CREATE OR REPLACE PROCEDURE VR_AD_INTEGRATION_EXPORT AS
l_v_file UTL_FILE.file_type;
l_filename varchar2(128);
f_exists boolean;
f_size pls_integer;
f_blk_size pls_integer;
BEGIN
l_filename := 'HRMtoAD1_'||to_char(sysdate,'YYYYMMDD')||'_'||to_char(sysdate,'HH24MISS');
l_v_file := UTL_FILE.fopen('integration', l_filename , 'w', 32767);
FOR x IN (SELECT * FROM (SELECT
decode(pid, NULL, RPAD(' ',7,' '), RPAD(user_id, 7, ' '))|| '' || decode(name_last, NULL, RPAD(' ',50,' '), RPAD(name_last, 50, ' '))
str
FROM vr_ad_integration
WHERE integrated = 'N') str
WHERE rownum <= 1000 ORDER BY rownum) LOOP
BEGIN
UTL_FILE.put_line(l_v_file, x.str);
END;
END LOOP;
utl_file.fgetattr('integration', l_filename , f_exists, f_size, f_blk_size);
if f_size > 0 then
UTL_FILE.fflush(l_v_file);
UTL_FILE.fclose(l_v_file);
else
UTL_FILE.fclose(l_v_file);
utl_file.fremove('integration', l_filename);
end if;
END VR_AD_INTEGRATION_EXPORT;
There is some useful functionality in the UTL_FILE package beyond reading and writing lines. I suggest you read the documentation to find out more.

Answer 2

Use a flag to check if the file is created, and only create it once on the first run through your loop. Pseudocode:
bool fileCreatedFlag = false;
for x in (SELECT ...):
if(!fileCreatedFlag):
l_v_file = fopen(...);
fileCreatedFlag = true;
put_line(...);
if(fileCreatedFlag):
fflush;
fclose;