Independent practice · SQLite

List products needing a physical count

Practice dataset

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Your task

Return sku sorted ascending for NULL on_hand only.
Exclude known zero counts.

Pass every output check to complete this task. Suggested active time: 10 minutes. You can keep working after that.

Required output

Return exactly these columns in this order.

skustring

Expected output: 1 rows. Keep the requested row order.

Values, data types and the number of copies of each row must match. A missing value is distinct from zero and from an empty string.

Preserve SQL NULL unless the task explicitly gives a replacement rule. Check JOINs for extra copies of rows.

Reconciliation checks

Every requested business key appears once.
Preserve SQL NULL and exact output column names.

Need a next step?

Hint 1: where to start

Use the NULL predicate.

Hint 2: build the method

Do not compare to zero.

Hint 3: check your work

WHERE on_hand IS NULL preserves the distinction.

How your work is checked

Every output check must pass. The score shows how much matched and helps you find mistakes; completion comes from passing all checks. Active time is recorded separately.

Passing records a correct practice output on this device. It is not a professional certification.

Source materials

19 original source records.

Data dictionary

stock.sku text: Unique product key, including discontinued items needing review.
stock.on_hand integer | null: Physical units. NULL requires a recount and must stay unknown.
stock.reserved integer: Committed units; more than known stock is a count conflict.
stock.reorder_point integer: Reorder only when projected position is strictly below this number.
stock.target integer: Target units after replenishment.
stock.pack_size integer: Positive supplier pack size; round an order up to complete packs.
inbound.po_id text: PO key; collapse exact duplicates and reject all conflicting variants.
inbound.sku text: May be unmatched; orphan inbound never creates a stock SKU.
inbound.units integer: Positive units on the order.
inbound.eta text: ISO arrival date; confirmed arrivals on or before cutoff count.
inbound.status text: Only confirmed arrivals contribute.

View database setup and records

CREATE TABLE stock (sku TEXT, on_hand INTEGER, reserved INTEGER, reorder_point INTEGER, target INTEGER, pack_size INTEGER);
INSERT INTO stock VALUES
('SKU-100',NULL,0,10,30,4),
('SKU-101',11,1,10,35,6),
('SKU-102',0,0,10,40,10),
('SKU-103',1,4,10,30,4),
('SKU-104',4,4,10,35,6),
('SKU-105',5,5,10,40,10),
('SKU-106',6,6,10,30,4),
('SKU-107',7,7,10,35,6);
CREATE TABLE inbound (po_id TEXT, sku TEXT, units INTEGER, eta TEXT, status TEXT);
INSERT INTO inbound VALUES
('PO-100','SKU-100',4,'2026-10-01','cancelled'),
('PO-101','SKU-101',5,'2026-10-02','confirmed'),
('PO-102','SKU-102',6,'2026-10-03','confirmed'),
('PO-103','SKU-103',7,'2026-10-04','confirmed'),
('PO-104','SKU-104',8,'2026-10-05','confirmed'),
('PO-105','SKU-105',9,'2026-10-06','confirmed'),
('PO-106','SKU-106',10,'2026-10-07','confirmed'),
('PO-101','SKU-101',5,'2026-10-02','confirmed'),
('PO-102','SKU-102',999,'2026-10-03','confirmed'),
('EDGE-100','SKU-104',7,'2026-10-07','confirmed'),
('ORPH-100','UNKNOWN',40,'2026-10-07','confirmed');

Your work

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SQL query

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Show the reference answer

SELECT sku FROM stock WHERE on_hand IS NULL ORDER BY sku

Unknown counts need a recount. A zero stock value is a measured quantity.