The PostgreSQL IN operator is used with the WHERE clause to check against a list of values.
The syntax for using IN operator with the WHERE clause to check against a list of values which returns a boolean value depending upon the match is as below:
Syntax: value IN (value1, value2, …)
The syntax for using IN operator to return the matching values in contrast with the SELECT statement is as below:
Syntax: value IN (SELECT value FROM tbl_name);
Now, let’s look into a few examples.
Here we will make a query for the rental information of customer id 10 and 12, using the WHERE clause and IN operator.
SELECT customer_id, rental_id, return_date FROM rental WHERE customer_id IN (10, 12) ORDER BY return_date DESC;
Here we will make a query for a list of customer id of customers that has rental’s return date on 2005-05-27.
SELECT first_name, last_name FROM customer WHERE customer_id IN ( SELECT customer_id FROM rental WHERE CAST (return_date AS DATE) = '2005-05-27' );