我正在嘗試了解物件關系技術并創建父型別：
CREATE OR REPLACE TYPE STUDENT
AS OBJECT(
FIO VARCHAR2(200),
Bday DATE,
Pas_Id NUMBER(20),
Address VARCHAR2(50))
NOT INSTANTIABLE
NOT FINAL;
孩子型別：
CREATE OR REPLACE TYPE BACH
UNDER STUDENT(
fieldOfStud varchar2(200),
Group_N number(4),
ege number(4),
GPA number(4),
MEMBER FUNCTION year_N RETURN NUMBER);
--тело типа бакалавр
CREATE OR REPLACE TYPE BODY BACH IS
MEMBER FUNCTION year_N RETURN NUMBER IS
BEGIN
IF SUBSTR(Group_N, 1, 1) BETWEEN 1 and 4 THEN
RETURN SUBSTR(Group_N, 1, 1);
END IF;
RETURN 0;
END;
END;
創建的表：
CREATE TABLE Students_Table(
SID NUMBER CONSTRAINT id_pk PRIMARY KEY,
stdt STUDENT
);
和插入的資料。我 100% 確定它存在。我想更新表和更改組，例如，從 5231 到 6231：
update Students_Table st
set TREAT(stdt as maga).Group_N = TREAT(stdt as maga).Group_N 1000
where TREAT(stdt AS MAGA).Pas_Id = 241122
但得到錯誤
ORA-00927: missing equal sign
uj5u.com熱心網友回復：
您需要在陳述句的前面應用轉換，以便更新只看到子型別：
update ( select s.sid, treat(stdt as bach) as stdt from students_table s ) st
set st.stdt.group_n = st.stdt.group_n 1000
where st.stdt.pas_id = 241122;
資料庫小提琴
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