Understanding Primary Keys | Dataford Interview Questions

What is a primary key?

Using the provided inventory_items table, identify the column designated as its primary key and write a query that returns that key for every row. The result should demonstrate that each returned key is unique and non-null.

Output

One row per inventory item.
Return the primary key column as primary_key.
Sort by primary_key in ascending order.

Schema

inventory_items

Column	Type	Description
item_idPK	INT	Unique identifier for the inventory item
item_name	VARCHAR(100)	Name of the inventory item
department	VARCHAR(50)	Merchandising department
quantity_on_hand	INT	Current quantity available

Your question is Understanding Primary Keys. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

What is a primary key?

Output

One row per inventory item.
Return the primary key column as primary_key.
Sort by primary_key in ascending order.

Schema

inventory_items

Column	Type	Description
item_idPK	INT	Unique identifier for the inventory item
item_name	VARCHAR(100)	Name of the inventory item
department	VARCHAR(50)	Merchandising department
quantity_on_hand	INT	Current quantity available

Your question is Understanding Primary Keys. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.