Sql Error in Select statement when doing subquery

Question

Hi,
I am trying to see what the error is in the subquery part of the select statement.
Subquery should be fetching the safety_stock_quantity based on the MAX(effectivity_date).
Any suggestions?
SELECT kbn.last_update_date,itm.segment1,itm.description,kbn.kanban_card_number,kbn.kanban_size,
               (SELECT msc.safety_stock_quantity
FROM mtl_safety_stocks msc
WHERE msc.effectivity_date = (select MAX(msc2.effectivity_date)
               from mtl_safety_stocks msc2
                                        where msc2.inventory_item_id = itm.inventory_item_id
                                             and msc2.organization_id = itm.organization_id)
               AND msc.inventory_item_id = itm.inventory_item_id
     AND msc.organization_id = itm.organization_id                                        
FROM mtl_system_items_b itm
,mtl_onhand_quantities_detail moqd
          ,mtl_safety_stocks msc
          ,mtl_kanban_card_activity kbn
WHERE itm.inventory_item_id = kbn.inventory_item_id
AND itm.organization_id = kbn.organization_id
AND itm.inventory_item_id = moqd.inventory_item_id
AND itm.organization_id = moqd.organization_id
AND moqd.subinventory_code = kbn.source_subinventory
     AND kbn.card_status = 1
     AND kbn.supply_status = 5
     AND msc.inventory_item_id = itm.inventory_item_id
     AND msc.organization_id = itm.organization_id     
GROUP BY
kbn.last_update_date,itm.segment1,itm.description,kbn.kanban_card_number,kbn.kanban_size;
Thanks
Pravn

Answer 1

Hi, Pravn,
Remember the ABC's of GROUP BY:
When you use a GROUP BY clause and/or an aggregate fucntion, then every item in the SELECT clause must be:
(A) an <b>A</b>ggregate function,
(B) one of the "group <b>B</b>y" expressions,
(C) a <b>C</b>onstant, or
(D) something that <b>D</b>epends entirely on the above. (For example, if you "GROUP BY TRUNC(dt)", you can "SELECT TO_CHAR (TRUNC(dt), 'Mon-DD')").
There's a GROUP BY clause in your main query, so every item in the main SELECT clause must be one of the above. The last item, the unnamed scalar sub-query, is none of the above.
How can you fix this problem? That depends on your data, the results you want, and perhaps on your Oracle version. If you'd like help, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) from all tables involved. Also post the results you want from that data, and an explanation of how you get those results from that data, with specific examples.
Always say which version of Oracle you're using.
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