Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE customers (customer_id VARCHAR); CREATE TABLE customer_events (customer_id VARCHAR)
### Question:
How many customers did not have any event?
### Answer:
SELECT COUNT(*) FROM customers WHERE NOT customer_id IN (SELECT customer_id FROM customer_events)