IN: a list of values

Marketing needs products from a few specific categories — "Books" and "Clothing" — for a themed selection. Writing OR for each category is tiring.

A list instead of a pile of ORs

When you need to check whether a value matches one of several, instead of a long chain of OR it's handier to use IN with a list:

SELECT name, category 
FROM products
WHERE category IN ('Electronics', 'Home');

This is a shorter, more readable form of category = 'Electronics' OR category = 'Home'. The negation is NOT IN (the value is not in the list).

Careful: if a NULL turns up in a NOT IN list, the result can become empty (we'll cover the subtleties of NULL later).

You need products from the "Books" and "Clothing" categories. Output their name and category.

Summary