Latest Inventory Snapshot per Store

SQL practice question · Hard · Data Cleaning · Walmart

The inventory feed sends repeated snapshots for each (store, item). Rows with NULL `on_hand` are corrupt and must be ignored. The current state of an item is its latest valid snapshot by `snapshot_ts`; if two valid snapshots share the same timestamp, the one with the higher `load_id` wins. Return per store: `store_id`, `items_tracked` (items with a valid current state), `items_out_of_stock` (current on_hand = 0), `units_on_hand` (sum of current on_hand). Order by `store_id`.

Table: inventory_feed

Schema of inventory_feed
ColumnType
store_idINTEGER
item_idINTEGER
on_handINTEGER
snapshot_tsTIMESTAMP
load_idINTEGER
Sample rows of inventory_feed
store_iditem_idon_handsnapshot_tsload_id
1100202026-10-01 06:00:001
1100122026-10-02 06:00:002
110152026-10-01 06:00:001
110102026-10-02 06:00:002
110272026-10-02 06:00:002
210002026-10-01 06:00:001
210092026-10-02 06:00:002
210342026-10-02 06:00:002
Expected output on the sample data
store_iditems_trackeditems_out_of_stockunits_on_hand
13119
22013

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