022 SQL IN

The current webpage explains the SQL IN operator. Here are the key points:

The IN operator is used in SQL to specify multiple possible values in a WHERE clause, making it a concise alternative to writing several OR conditions.

Syntax Example:

SELECT column_name(s)
FROM table_name
WHERE column_name IN (value1, value2, ...);

Sample Query: To select customers from Germany, France, or UK:

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

Adding the NOT keyword (i.e., NOT IN) reverses the logic, returning all records not matching the listed values.
The IN operator can also be used with subqueries. For example, to find customers that match IDs returned by another query:
```
SELECT *
FROM Customers
WHERE CustomerID IN (SELECT CustomerID FROM Orders);
```
The site provides interactive SQL examples and an exercise question testing the purpose of the IN operator.

This page is structured as part of a broader SQL tutorial resource and includes links to related SQL topics and exercises.[1]

SQL IN Operator

The IN operator allows you to specify multiple values in a WHERE clause.

The IN operator is a shorthand for multiple OR conditions.

Return 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, ...);

Below is a selection from the Customers table used 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 using the NOT keyword in front of the IN operator, you return all records that are NOT any of the values in the list.

Return all customers that are NOT from 'Germany', 'France', or 'UK':

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

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

With a subquery you can return all records from the main query that are present in the result of the subquery.

Return all customers that have an order in the Orders table:

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

The result in the example above returned 74 records, that means that there are 17 customers that haven't placed any orders.

Let us check if that is correct, by using the NOT IN operator.

Return all customers that have NOT placed any orders in the Orders table:

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