How to loop through keys values | Oracle | - sql

Question

I am stuck with this approach not getting. How do I need to go with it.
I have table which as column -> KEYS. This as more then 500+ keys
Like below the data would be :
KEYS
12RTY
UIIJ9
GHSJ8
HJSKI
I should not be making use of cursor need to loop one by one values from column : KEYS to my PLSQL logic
This is how I want to convert that data to comma separated format and used in my loop to read one by one value
(key1,key2,key3....)
My code :
DECLARE
v_name varchar2(10 char);
BEGIN
FOR v_counter in 1..(key1,key2,key3..) LOOP
select NAME into v_name from EMP where KEY=v_counter;
DBMS_OUTPUT.PUT_LINE(v_name)
END;
END;
I would have made use of list_agg but only 10 values can be created as comma separated.
More then that it throws error like exceeded 4000

Answer 1

You can use a cursor:
DECLARE
v_name varchar2(10 char);
BEGIN
FOR v_row IN (SELECT key FROM your_key_table)
LOOP
select NAME into v_name from EMP where KEY=v_row.key;
DBMS_OUTPUT.PUT_LINE(v_name);
END LOOP;
END;
/
But you could combine the two queries into one:
DECLARE
v_name varchar2(10 char);
BEGIN
FOR v_row IN (SELECT e.name
FROM your_key_table ykt
INNER JOIN emp e
ON (ykt.key = e.key)
ORDER BY ykt.key)
LOOP
DBMS_OUTPUT.PUT_LINE(v_row.name);
END LOOP;
END;
/
db<>fiddle here

Answer 2

Instead of using a cursor, you can use BULK COLLECT to store all of the keys into a collection, then loop through that collection selecting and printing the data you are looking for.
DECLARE
TYPE keys_t IS TABLE OF your_schema.key_table.keys%TYPE;
l_keys keys_t;
l_name your_schema.emp.name%TYPE;
BEGIN
SELECT keys
BULK COLLECT INTO l_keys
FROM your_schema.key_table;
FOR i IN 1 .. l_keys.COUNT
LOOP
SELECT NAME
INTO l_name
FROM EMP
WHERE KEY = l_keys (i);
DBMS_OUTPUT.PUT_LINE (l_name);
EXCEPTION
WHEN NO_DATA_FOUND THEN
NULL; --No employee exists with that key
END LOOP;
END;
If you are just trying to tie the keys to EMPs, it would probably make more sense to just do a join.