支持时间间隔操作语法
CREATE TABLE coupons1 (
coupon_id INTEGER CONSTRAINT coupons1_pk PRIMARY KEY,
name VARCHAR2(30) NOT NULL,
duration INTERVAL DAY TO SECOND
);
CREATE TABLE coupons (
coupon_id INTEGER CONSTRAINT coupons_pk PRIMARY KEY,
name VARCHAR2(30) NOT NULL,
duration INTERVAL YEAR TO MONTH
);
