What does the MySQL COALESCE() function return if all arguments supplied to it are NULL?

If all values ​​in the MySQL COALESCE() function are NULL, it returns NULL as output. This means that the function did not find any non-NULL value in the list.

Example

mysql> Select COALESCE(NULL, NULL, NULL, NULL);
+----------------------------------+
| COALESCE(NULL, NULL, NULL, NULL) |
+----------------------------------+
|                             NULL |
+----------------------------------+

1 row in set (0.00 sec)

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