Recyclable and Low Fat Products

Recyclable and Low Fat Products

What is this problem about?

The Recyclable and Low Fat Products SQL problem asks you to find all product IDs where the product is both recyclable ('Y') AND low fat ('Y'). This is the simplest possible SQL filtering problem — a WHERE clause with two AND conditions. The database interview pattern is demonstrated at its most basic.

Why is this asked in interviews?

Apple, Uber, Microsoft, Meta, Amazon, Google, Bloomberg, and Adobe ask this as a first SQL warm-up to verify basic filtering syntax and logical operators.

Algorithmic pattern used

Simple WHERE with AND.

SELECT product_id FROM Products WHERE recyclable = 'Y' AND low_fats = 'Y'

Example explanation

Products: (0,'Y','Y'), (1,'Y','N'), (2,'N','Y'), (3,'Y','Y'). Filter: recyclable='Y' AND low_fats='Y'. Product IDs: 0 and 3. Result: [0, 3].

Common mistakes candidates make

• Using OR instead of AND (returns too many products).
• Quoting 'Y' incorrectly for different SQL dialects.
• Selecting all columns when only product_id is needed.
• Using a JOIN when a simple WHERE suffices.

Interview preparation tip

Recyclable and Low Fat Products is a reminder that SQL interviews start with fundamentals. Master WHERE with AND, OR, NOT, IN, BETWEEN. This specific problem also appears as a "data filter" design pattern in data pipelines. Always verify: which logical operator connects the conditions? AND requires BOTH conditions true; OR requires AT LEAST ONE.