THE IN OPERATOR | SQL Basics

You've already seen how to filter rows with comparison operators (=, >, <), AND/OR/NOT, BETWEEN, and LIKE. The IN operator is another WHERE-clause tool for a very common situation: checking whether a column's value matches any one of several specific values.

The problem IN solves

Suppose you want customers from India, France, or Brazil. Without IN, you'd chain OR:

SELECT * FROM customers
WHERE country = 'India' OR country = 'France' OR country = 'Brazil';

That works, but it gets repetitive fast — the column name is typed three times just to check three values. IN lets you write the same condition more compactly:

SELECT * FROM customers
WHERE country IN ('India', 'France', 'Brazil');

Both queries return exactly the same rows. IN is shorthand for "equals any of these values" — nothing more.

Syntax

WHERE column IN (value1, value2, value3, ...)

The values go in parentheses, separated by commas.
Strings are quoted ('India'), numbers are not (IN (1, 2, 3)).
The list can be as short as one value or as long as you need.

NOT IN

Just like other conditions, you can negate it with NOT:

SELECT * FROM customers
WHERE country NOT IN ('India', 'France', 'Brazil');

This returns every customer except those three countries.

Combining with other conditions

IN works alongside AND/OR just like any other condition:

SELECT * FROM invoices
WHERE billing_country IN ('USA', 'Canada')
  AND total > 10;

A heads-up for later

Once you get to NULL values later in this course, keep this in mind: if the list inside a NOT IN (...) could ever contain a NULL, the whole condition can unexpectedly match zero rows. You don't need to worry about this yet — just flag it as something to be careful about once NULLs are in the picture.

Recap

IN checks a column against a list of values — it's shorthand for multiple OR-chained equality checks.
NOT IN is the negated version — "none of these values."
Both work anywhere a normal WHERE condition works, including combined with AND/OR.