Independent practice · SQLite

Calculate available units

Practice dataset

My saved work →

Your task

Return sku, available for every stock SKU, sorted by sku.
available = on_hand - reserved. Preserve NULL and negative results.

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
availableNULL or number

Expected output: 8 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

Subtract reserved from on_hand.

Hint 2: build the method

SQL propagates NULL through this arithmetic.

Hint 3: check your work

Do not use COALESCE or MAX(...,0).

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

Active 0:00 · Paused 0s

SQL query

Import answer

Keep a handoff you can replay

Check your current answer, then download the output and its report. The report includes the source, answer and each check so you can review what passed and what needs work.

To replay your work, open this task with the same dataset, import your answer and check it again.

Show the reference answer

SELECT sku,on_hand-reserved AS available FROM stock ORDER BY sku

Clipping or defaulting would hide the cases that operations needs to investigate.