Exemple FIRST_DAY

Example 1. Utilisation de la fonction FIRST_DAY
SELECT FIRST_DAY(OF MONTH FROM current_date) FROM rdb$database;
SELECT FIRST_DAY(OF YEAR FROM current_timestamp) FROM rdb$database;
SELECT FIRST_DAY(OF WEEK FROM date '2022-11-01') FROM rdb$database;
Voir aussi :

LAST_DAY().