Items with Negative Quantity

This query can give list of items that have negative quantity in either cost layers table or onhand quantity table.
.

 SELECT b.organization_id
      , b.concatenated_segments
      , b.description
      ,  cst_qty
      , onhand_qty
   FROM (SELECT 'cst'
              , organization_id
              , inventory_item_id
              , layer_quantity cst_qty
              , 0 onhand_qty
           FROM apps.cst_quantity_layers
          WHERE layer_quantity < 0 
         UNION ALL
         SELECT 'onhand'
              , organization_id
              , inventory_item_id
              , 0
              , b.transaction_quantity  
           FROM apps.mtl_onhand_quantities b
          WHERE b.transaction_quantity  < 0 
        ) A
        , apps.mtl_system_items_vl b
  WHERE A.organization_id = b.organization_id
    AND a.inventory_item_id = b.inventory_item_id;