SQL IN

The SQL IN Operator

The IN operator, utilized within a WHERE clause, enables specification of multiple values.

It functions as a shorthand for multiple OR conditions.

Retrieve all customers from ‘Germany’, ‘France’, or ‘UK’.

SELECT * FROM Customers
WHERE Country IN (‘Germany’, ‘France’, ‘UK’);

SELECT column_name(s)

FROM table_name

WHERE column_name IN (value1, value2, ...);'

Here is a sample from the Customers table utilized in the examples:

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	05021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	05023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden

By placing the NOT keyword in front of the IN operator, you retrieve all records that are not any of the values in the list.

Retrieve all customers who are not from ‘Germany’, ‘France’, or ‘UK’.

SELECT * FROM Customers
WHERE Country NOT IN (‘Germany’, ‘France’, ‘UK’);

You can also employ the IN operator with a subquery in the WHERE clause.

Using a subquery enables the retrieval of all records from the main query that are present in the result of the subquery.

Retrieve all customers who have placed an order in the Orders table.

SELECT * FROM Customers
WHERE CustomerID IN (SELECT CustomerID FROM Orders);

The outcome in the example provided yielded 74 records, indicating that there are 17 customers who haven’t placed any orders.

Let’s confirm this by using the NOT IN operator.

Retrieve all customers who have not placed any orders in the Orders table.

SELECT * FROM Customers
WHERE CustomerID NOT IN (SELECT CustomerID FROM Orders);