2

我正在尝试了解对象关系技术并创建父类型：

CREATE OR REPLACE TYPE STUDENT
AS OBJECT(
    FIO VARCHAR2(200),
    Bday DATE,
    Pas_Id NUMBER(20),
    Address VARCHAR2(50))
NOT INSTANTIABLE
NOT FINAL;

孩子类型：

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;

创建的表：

CREATE TABLE Students_Table(
SID  NUMBER CONSTRAINT id_pk PRIMARY KEY,
stdt STUDENT
);

并插入数据。我 100% 确定它存在。我想更新表和更改组，例如，从 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

但得到错误

ORA-00927: missing equal sign
4

1 回答 1

1

您需要在语句的前面应用转换，以便更新只看到子类型：

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;

DB小提琴

于 2021-12-26T11:15:18.987 回答