Solutions:
Check these solutions from our community and artificial intelligence:
The solution is correct and demonstrates a level of completeness. It solves the problem and uses the correct approach.
The candidate's solution is incomplete - it does not return the expected output. The candidate has correctly identified that a join is needed to combine the data from the three tables, but has not included all the necessary conditions in the WHERE clause.
A better approach would be to use a LEFT JOIN and check for NULL values in the products table, as this would return all customers who have placed an order for a product that is out of stock.