COALESCE

Provide a default value for NULL with COALESCE.

COALESCE returns the first non-NULL value from a list. It is used to give a default instead of NULL.

SELECT COALESCE(phone, 'yok') AS tel FROM customers;

This query writes 'yok' when phone is null.

COALESCE(phone, 'yok') AS tel is selected from customers.

COALESCE — details

You can give several fallbacks: COALESCE(a, b, c). If all are NULL the result is NULL. Ideal for filling empty cells in reports.

Select phone with 'none' as fallback aliased as tel from customers.

Show example solution

SELECT COALESCE(phone, 'yok') AS tel
FROM customers

Fallback value

SELECT ____(phone, 'yok') FROM customers;

Show answer

SELECT COALESCE(phone, 'yok') FROM customers;

Next lesson: NULLIF