我已经完成了以下操作,并且在创建体型时遇到了问题。请帮忙!!
SQL> desc theater_t
Name Null? Type
----------------------------------------- -------- ----------------------------
TNO NUMBER
NAME VARCHAR2(15)
ADDRESS ADDRESS_TY
PHONE PH_TY
START_DATE DATE
END_DATE DATE
METHOD
------
MEMBER FUNCTION FEATURED_DAYS RETURNS NUMBER
SQL> desc theaters
Name Null? Type
----------------------------------------- -------- ----------------------------
TNO NUMBER
NAME VARCHAR2(15)
ADDRESS ADDRESS_TY
PHONE PH_TY
START_DATE DATE
END_DATE DATE
SQL> desc nowshowing
Name Null? Type
----------------------------------------- -------- ----------------------------
FILM NOT NULL NUMBER
THEATER REF OF THEATER_T
Theatres 是一个类型为theater_t 的表。我想创建一个返回 end_date-start_date 的 features_days。但我做不到。