PL/SQL - where to update and where to rollback - sql

Question

I'm pretty new to PL/SQL and I have to work with it a lil bit. I had to make some functions which are pretty similar. I simplified it for this question.
I got 2 tables (called them TABLE1, TABLE2 in this example) which have some data. I have to trim, validate the data and insert it into other tables.
TABLE1 -> TABLE3
TABLE2 -> TABLE4
TABLE1 has some orders, while TABLE2 has several positions for each order. As I said its simplfied so I haven't posted things like the exception or the open/close cursors etc. Atm it works like this but I don't think this structure is somewhere near "best-practise" but I didn't found any PL/SQL code on the web which covered this problem, though it must be something pretty common.
COMMIT could be at the end of the outer loop I guess, maybe its even after the whole function.
So could you tell me if its okay like this or completely stupid and what I should/could change and why. I don't wanna get used to a 'bad' codingstyle so I wanna learn it the right way while I'm a beginner at it.
Heres the simplified code:
BEGIN
SAVEPOINT SAVE_Stufe_5;
LOOP
SAVEPOINT SAVE_LOOP;
FETCH CURSOR1 INTO RECORD1;
EXIT WHEN CURSOR1%NOTFOUND OR CURSOR1%NOTFOUND IS NULL;
vError := 0;
RECORD1 := CURSOR1;
-- DATAVALIDATION (vError will be the Errorcode)
IF (vError = 0) THEN
retcode := InsertTABLE3(RECORD1);
IF (retcode != DATABASE_OK) THEN
ROLLBACK TO SAVE_LOOP;
END IF;
END IF;
LOOP
FETCH CURSOR2 INTO CURSOR2;
EXIT WHEN CURSOR2%NOTFOUND OR CURSOR2%NOTFOUND IS NULL OR vError != 0 OR retcode != DATABASE_OK;
RECORD2 := CURSOR2;
-- DATAVALIDATION (vError will be the Errorcode)
IF (vError = 0) THEN
retcode := InsertTABLE4(RECORD2);
IF (retcode = DATABASE_OK) THEN
UPDATE TABLE2
SET TABLE2.Status = 20
WHERE TABLE2.ID = CURSOR2.ID;
ELSE
ROLLBACK TO SAVE_LOOP;
END IF;
END IF;
END LOOP;
IF (vError = 0) THEN
UPDATE TABLE1
SET TABLE1.Status = 20
WHERE TABLE1.ID = CURSOR1.ID
ELSE
ROLLBACK TO SAVE_LOOP;
UPDATE TABLE1
SET TABLE1.Status = vError
WHERE TABLE1.ID = CURSOR1.ID
UPDATE TABLE2
SET TABLE2.Status = vError
WHERE TABLE2.ID = CURSOR2.ID
END IF;
END LOOP;
END;
Small update:
I managed to do the validation set-based, though I don't really know how to get my data into the other table. I tried a insert select with the trim in it but that only inserts one row. If I would use a implicit cursor as suggested I still had to loop, I wouldn't loop the cursor but the SELECT INTO as far as the implicit cursor only has one row.
I guess I could really need a snippet or some link to help me out. Here's a simplified version of my try:
INSERT INTO TABLE3
(
val1,
val2,
val3
)
SELECT TRIM(val1),
TRIM(val2),
TRIM(val3),
FROM TABLE1
WHERE STATUS = 10
AND (TRIM(PK1) || TRIM(PK2)) NOT IN (SELECT (TABLE3.PK1 || TABLE3.PK2) FROM TABLE3);

Answer 1

Generally speaking, it is bad style to do things by looping in SQL. A loop like this will be extremely slow compared to a set-based solution. Instead of all these loops, it would be preferable to use a single insert or merge statement to copy all of table 1 into table 3--or perhaps a few statements if your validation is complex and you need some intermediate steps.
Most types of trimming and data validation you would want to do can be handled like this. Almost never do you need nested loops. There are exceptions, but they are rare. Those who are new to SQL tend to use loops because that is what we know from other languages. I was in that category not so long ago. But to really use the power of the language, you have to get beyond that.
Beyond this general point, not much specific help can be given if we don't know anything about the tables or what kind of validation you are doing.
When you should commit is also dependent on your specific design and what you are trying to accomplish.