Inserting values in a table in FOR loop statement in pl sql - sql

Question

I want to run the loop from i=1 to i=12 and insert each value of M_1,M_2 and so on till M_12 in M_Maintenance table.I have tried but it is not working.Please help me out.
The code which I have tried is:-
BEGIN
FOR i IN 1 .. 12
LOOP
DECLARE
M_i NUMBER;
MONTH_i_COUNT NUMBER;
M_i_Maintenance NUMBER;
MONTH_i_SUM NUMBER;
BEGIN
SELECT ROUND (
( ( (SELECT SUM (MONTH_i_COUNT)
FROM XXBAXY.XXBAXY_BREAKDOWN_TAB
WHERE LOSS_CAT = 'Maintenance Related Losses')
+ (SELECT MONTH_i_COUNT
FROM XXBAXY.XXBAXY_BREAKDOWN_TAB
WHERE LOSS_CAT = 'Maintenance Related Losses'
AND description = 'SAFTY SHEET PRO. ')
- (SELECT MONTH_i_COUNT
FROM XXBAXY.XXBAXY_BREAKDOWN_TAB
WHERE LOSS_CAT = 'Maintenance Related Losses'
AND description =
'PREVENTIVE MAINTENANCE '))
/ (SELECT MONTH_i_SUM FROM XXBAXY.XXBAXY_ATTR_SUM_TAB))
* 100,
3
)
INTO M_i
FROM DUAL;
EXCEPTION
WHEN ZERO_DIVIDE
THEN
M_i := 0;
END;
INSERT INTO M_Maintenance (M_i_Maintenance)
VALUES (M_i);
END LOOP;
END;

Answer 1

Let's first make your query easier to read and better perfoming, if I don't mistake it should be this one:
SELECT ROUND(
SUM(CASE description
WHEN 'SAFTY SHEET PRO. ' THEN 2*MONTH_i_COUNT
WHEN 'PREVENTIVE MAINTENANCE ' THEN -MONTH_i_COUNT
ELSE MONTH_i_COUNT
END) / MIN(MONTH_i_SUM) *100, 3)
FROM XXBAXY.XXBAXY_BREAKDOWN_TAB
CROSS JOIN XXBAXY.XXBAXY_ATTR_SUM_TAB
WHERE LOSS_CAT = 'Maintenance Related Losses'
In this case your PL/SQL code can look like this (skipping the exception handler):
DECLARE
m NUMBER;
sqlstr VARCHAR2(1000);
BEGIN
FOR i IN 1..12 LOOP
sqlstr :=
'SELECT ROUND( '
' SUM(CASE description '
' WHEN ''SAFTY SHEET PRO. '' THEN 2*MONTH_'||i||'_COUNT '
' WHEN ''PREVENTIVE MAINTENANCE '' THEN -MONTH_'||i||'_COUNT '
' ELSE MONTH_'||i||'_COUNT '
' END) / MIN(MONTH_'||i||'_SUM) *100, 3) '
'FROM XXBAXY.XXBAXY_BREAKDOWN_TAB '
' CROSS JOIN XXBAXY.XXBAXY_ATTR_SUM_TAB '
'WHERE LOSS_CAT = ''Maintenance Related Losses''';
EXECUTE IMMEDIATE sqlstr INTO m;
EXECUTE IMMEDIATE 'INSERT INTO M_Maintenance (M_'||i||'_Maintenance) VALUES (:m)' USING m;
END LOOP;
END;

Answer 2

Did you mean, that your table XXBAXY.XXBAXY_BREAKDOWN_TAB contains fields MONTH_1_COUNT, MONTH_2_COUNT, MONTH_3_COUNT and so on? If so, first step should be is redesigning this table because of violation of 1NF. It's bad design, a way of immutable pain. If no, it's unclear why you try to use uninitialized local varables in SQL statement without any field references.
Generally it looks that you should avoid a FOR LOOP and PL/SQL and write a single insert/select statement which will produces all rows required.
Elaborating: your source has a common structure of
begin
for i in MIN..MAX loop
select something into value
from table1
where some_condition
and id = i;
insert into table2 values (value);
end loop;
end;
Almost always better way is do this as
insert into table2
select something
from table1
where some_condition
and id in (MIN..MAX);