task Constraints · hard

Enforce the reservation boundary

Create safe_reservations with shopper_id, item_id and quantity. Load the latest valid feed row for each shopper/item pair, then return the loaded rows. Valid input has existing shopper and item keys and an integer-stored quantity from 1 through 5.

what to return

Columns

shopper_iditem_idquantity in this order

Rows

3 rows · in the order asked

Watch for

Filter invalid feed rows before choosing greatest feed id per pair. A later invalid row must not suppress an earlier valid one.

The target must reject NULL keys, orphan keys, duplicate pairs, NULL quantity, fractional quantity and quantities outside 1–5; valid new rows must remain insertable.

Use a composite primary key, NOT NULL, foreign keys and a quantity CHECK including typeof(quantity). Order by shopper_id,item_id.

Skill

Separate staging cleanup from durable relational and domain constraints. Refresher: Stored procedures: parameters & contracts →

expected result

Your query should return exactly these columns and values. Run it and compare.

data you can query

Sample rows from each table. Each column shows its type underneath; → marks a link to another table.