Using arithmetic division in a PL/SQL Procedure - oracle

Question

My PL/SQL Procedure provides the values I want, in a CSV file. BUT I want to do some mathematical division using some of the values. I get no output in the relevant column though when I run the code and i'd like to know why.
I've tried putting the variable desctiption in the declaritive section of the procedure, and after 'BEGIN' and also using brackets in various places. The code compiles, and it runs. It just won't give any output in the column that I'm trying to get output for.
create or replace procedure THANOS is
--variables
l_dblink varchar2(100) := 'DB1';
TOTAL_ROW_COUNT varchar2(3000);
TOT_OBJECT_SIZE_MB varchar2(100);
EST_ONE_ROW varchar2(100);
file_handle UTL_FILE.file_type;
v_ts_name varchar2(30);
v_link_name varchar2(10);
v_csv_name varchar2(100);
--
begin
SELECT tablename into v_csv_name
FROM table_tracker
WHERE
CREATED_AT = (select MAX(CREATED_AT) from table_tracker);
EST_ONE_ROW := (TOTAL_ROW_COUNT / TOT_OBJECT_SIZE_MB);
select link_name into v_link_name from link_and_mail where mdate = (select max(mdate) from link_and_mail);
select distinct targetschema into v_ts_name from table;
file_handle := utl_file.fopen('ESTIMATES_CSV', v_csv_name||'_EST_PROC.csv', 'w', 32767);
UTL_FILE.PUT_LINE(file_handle, 'The below report shows total row counts in PROD');
UTL_FILE.PUT_LINE(file_handle, ' for all tables in the request:');
UTL_FILE.PUT_LINE(file_handle, ' ');
utl_file.put_line(file_handle, 'OWNER,TABLE_NAME,TOT_OBJECT_SIZE_MB,TOTAL_ROW_COUNT,EST_ONE_ROW');
for rws in (
select /*+parallel */ a.owner,a.table_name, sum(b.sum_bytes) TOT_OBJECT_SIZE_MB, EST_ONE_ROW
from dba_tables#DB1 a, V_SEG_DATA b
where a.table_name = b.segment_name
and a.table_name in
(select table_name from table)
and a.owner in (select distinct schema from table c)
group by a.owner,a.table_name
order by a.table_name
)
loop
execute immediate' select count(*) from ' ||rws.owner||'.'||rws.table_name || '#' || l_dblink into TOTAL_ROW_COUNT;
utl_file.put_line(file_handle,
rws.OWNER || ',' ||
rws.TABLE_NAME || ',' ||
rws.TOT_OBJECT_SIZE_MB || ',' ||
TOTAL_ROW_COUNT || ',' ||
EST_ONE_ROW
);
end loop;
utl_file.fclose(file_handle);
end THANOS;
The result of this code is to provide a .csv file with the following columns:
OWNER TABLE_NAME TOT_OBJECT_SIZE_MB TOTAL_ROW_COUNT EST_ONE_ROW
However, the EST_ONE_ROW column is always empty.
I want it to have the value for the number of rows divided by the total object size as per what is written:
EST_ONE_ROW := (TOTAL_ROW_COUNT / TOT_OBJECT_SIZE_MB);
Disclaimer -- People may say that this isn't a good way of finding what I'm trying to find, etc etc, but, it'd be great if no-one judged that, and just lead me in the right direction when it comes to what's wrong with the logic of the code itself, what I'm doing wrong with the 'division' logic
Thank you stackies!! :-)

Answer 1

They are all VARCHAR2 and are all empty. So there wouldn't be any result. This would be like this:
set serveroutput on
declare
TOTAL_ROW_COUNT varchar2(3000);
TOT_OBJECT_SIZE_MB varchar2(100);
EST_ONE_ROW VARCHAR2(100);
begin
EST_ONE_ROW := (TOTAL_ROW_COUNT / TOT_OBJECT_SIZE_MB);
dbms_output.put_line('EST_ONE_ROW:'||EST_ONE_ROW);
end;
Output:
EST_ONE_ROW:
PL/SQL procedure successfully completed.
But it look like EST_ONE_ROW is part of V_SEG_DATA so you might need to change the statement:
utl_file.put_line(file_handle,
rws.OWNER || ',' ||
rws.TABLE_NAME || ',' ||
rws.TOT_OBJECT_SIZE_MB || ',' ||
TOTAL_ROW_COUNT || ',' ||
rws.EST_ONE_ROW -- <<<<<<<<<<<<<<< change here
);
Another way if this is purely calculated:
utl_file.put_line(file_handle,
rws.OWNER || ',' ||
rws.TABLE_NAME || ',' ||
rws.TOT_OBJECT_SIZE_MB || ',' ||
TOTAL_ROW_COUNT || ',' ||
(TOTAL_ROW_COUNT / rws.TOT_OBJECT_SIZE_MB)
);
The above fails if TOT_OBJECT_SIZE_MB is zero. As you will get a division by zero failure. You might wnat to handle with an if statement.
So this might work:
create or replace procedure THANOS is
--variables
l_dblink varchar2(100) := 'DB1';
TOTAL_ROW_COUNT varchar2(3000);
TOT_OBJECT_SIZE_MB varchar2(100);
EST_ONE_ROW varchar2(100);
file_handle UTL_FILE.file_type;
v_ts_name varchar2(30);
v_link_name varchar2(10);
v_csv_name varchar2(100);
--
begin
SELECT tablename into v_csv_name
FROM table_tracker
WHERE
CREATED_AT = (select MAX(CREATED_AT) from table_tracker);
select link_name into v_link_name from link_and_mail where mdate = (select max(mdate) from link_and_mail);
select distinct targetschema into v_ts_name from table;
file_handle := utl_file.fopen('ESTIMATES_CSV', v_csv_name||'_EST_PROC.csv', 'w', 32767);
UTL_FILE.PUT_LINE(file_handle, 'The below report shows total row counts in PROD');
UTL_FILE.PUT_LINE(file_handle, ' for all tables in the request:');
UTL_FILE.PUT_LINE(file_handle, ' ');
utl_file.put_line(file_handle, 'OWNER,TABLE_NAME,TOT_OBJECT_SIZE_MB,TOTAL_ROW_COUNT,EST_ONE_ROW');
for rws in (
select /*+parallel */ a.owner,a.table_name, sum(b.sum_bytes) TOT_OBJECT_SIZE_MB, EST_ONE_ROW
from dba_tables#DB1 a, V_SEG_DATA b
where a.table_name = b.segment_name
and a.table_name in
(select table_name from table)
and a.owner in (select distinct schema from table c)
group by a.owner,a.table_name
order by a.table_name
)
loop
execute immediate' select count(*) from ' ||rws.owner||'.'||rws.table_name || '#' || l_dblink into TOTAL_ROW_COUNT;
if rws.TOT_OBJECT_SIZE_MB then
EST_ONE_ROW := TOTAL_ROW_COUNT / rws.TOT_OBJECT_SIZE_MB;
else
EST_ONE_ROW := null;
end if;
utl_file.put_line(file_handle,
rws.OWNER || ',' ||
rws.TABLE_NAME || ',' ||
rws.TOT_OBJECT_SIZE_MB || ',' ||
TOTAL_ROW_COUNT || ',' ||
EST_ONE_ROW
);
end loop;
utl_file.fclose(file_handle);
end THANOS;

Answer 2

Well, the way the procedure looks now (i.e. code you posted), there's no way that EST_ONE_ROW is anything but NULL. Its value is calculated at the beginning of the procedure, when both TOTAL_ROW_COUNT and TOT_OBJECT_SIZE_MB are NULL as well.
See if it helps if you put
EST_ONE_ROW := (TOTAL_ROW_COUNT / TOT_OBJECT_SIZE_MB);
into the loop, right before the UTL_FILE.put_line call as - at that moment - variables used to calculate its value probably aren't NULL any more.