SQL

sql in

Used alongside a WHERE clause as a shorthand for multiple OR conditions.
So instead of:
SELECT * FROM users
WHERE country = 'USA' OR country = 'United Kingdom' OR
country = 'Russia' OR country = 'Australia';
You can use:
SELECT * FROM users
WHERE country IN ('USA', 'United Kingdom', 'Russia',
'Australia');

in in sql

(IN) operator in sql like "OR" operator
For example: 
Select * From employees
Where department_id "IN" (60,90); 

SQL IN Operator

SELECT first_name, country
FROM Customers
WHERE country IN ('USA', 'UK');