使用Informix Version 14.10.FC10DE，我们可以：

CREATE TABLE my_dates
(
    date_required DATE
);

INSERT INTO my_dates VALUES ( '2023-08-20' );
INSERT INTO my_dates VALUES ( '2023-01-10' );

然后我们可以使用函数“TO_CHAR”来获取月份名称：

SELECT date_required, TO_CHAR( date_required, '%B') AS base_month FROM my_dates;

date_required  2023-08-20
base_month     August

date_required  2023-01-10
base_month     January

在线documentation：

Symbol  Meaning
%B      Full month name, as defined in the locale