? SELECT ... IN in SQL

The IN operator is used in the WHERE clause to filter rows where a column's value matches any value in a specified list or subquery.

? Syntax:

SELECT column1, column2, ...FROM table_nameWHERE column_name IN (value1, value2, value3, ...);

Or with a subquery:

SELECT column1, column2, ...FROM table_nameWHERE column_name IN (SELECT other_column FROM other_table WHERE condition);

? Examples:

Select employees in specific departments:

SELECT name, departmentFROM employeesWHERE department IN ('Sales', 'Marketing', 'HR');

Select products with IDs from another table:

SELECT product_nameFROM productsWHERE product_id IN (SELECT product_id FROM orders WHERE order_date > '2025-01-01');

? Notes:

• IN is a shorthand for multiple OR conditions.

  WHERE department = 'Sales' OR department = 'Marketing' OR department = 'HR'

• Can improve query readability and performance.

• When the list inside IN is empty, the condition returns no rows.

• Use with caution with NULL values, as NULL IN (… ) returns UNKNOWN (no match).

Want to see how IN compares with EXISTS or how to use it with subqueries?