Novice to DB - Oracle - sql

Question

I'm pretty new to Oracle and Database.
I'm trying to write a stored procedure with cursors. How do I write a select statement inside the cursor loop, and how do I loop through the result set that I get from the select inside that cursor loop?
For example:
Open Curs1;
Exit When Curs1%NotFound;
Loop
Select column1,column2 from table -- Returns multiple records. How to loop through this record set and perform CRUD operations.
End loop;
Close Curs1;

Answer 1

Use a FOR-loop cursor - they are faster and simpler than the open/fetch/close syntax.
begin
for results1 in
(
select ...
) loop
--Do something here
for results2 in
(
select ...
where some_table.some_column = results1.some_column
) loop
--Do something here
end loop;
end loop;
end;
/
Although this literally answers the question, you generally do not want to have loops inside loops like this. If possible, it would be better to combine the two SQL statements with a join and then loop through the results.

Answer 2

Try to use the following example that fetches rows one at a time from the cursor variable emp_cv into the user-defined record emp_rec:
declare
TYPE YourType IS ref cursor return YourTable%rowtype;
tab_cv YourType;
tab_rec YourTable%rowtype;
begin
loop
fetch tab_cv into emp_rec;
exit when tab_cv%notfound;
...
end loop;
end;
The BULK COLLECT clause lets you fetch entire columns from the result set, or the entire result set at once. The following example, retrieves columns from a cursor into a collection:
declare
type NameList IS table of emp.ename%type;
names NameList;
cursor c1 is select ename from emp where job = 'CLERK';
begin
open c1;
fetch c1 bulk collect into names;
...
close c1;
end;
The following example uses the LIMIT clause. With each iteration of the loop, the FETCH statement fetches 100 rows (or less) into index-by table acct_ids. The previous values are overwritten.
declare
type NumList is table of number index by binary_integer;
cursor c1 is select acct_id from accounts;
acct_ids NumList;
rows natural := 100; -- set limit
begin
open c1;
loop
/* The following statement fetches 100 rows (or less). */
fetch c1 bulk collect into acct_ids limit rows;
exit when c1%notfound;
...
end loop;
close c1;
end;

Answer 3

You need to declare the CURSOR and FETCH the records in the loop.
DECLARE
CURSOR curs1
IS
SELECT column1,
column2
FROM yourtable;
v_column1 yourtable.column1%TYPE;
v_column2 yourtable.column2%TYPE;
BEGIN
OPEN curs1;
LOOP
FETCH curs1
INTO v_column1,
v_column2;
EXIT
WHEN curs1%NOTFOUND;
INSERT INTO yourtable2(col1)VALUES( '000'||v_column1 );
-- A sample DML operation.
--Do other operations on individual records here.
END LOOP;
CLOSE curs1;
END;