帶對象類型的PL/SQL PRIMARY KEY

Question

我已經創建瞭如下的對象關係類型。

CREATE OR REPLACE TYPE familycar_t AS OBJECT (
make VARCHAR (10), 
model VARCHAR(10), 
year NUMBER (4), 
fuel_type VARCHAR (10)); 
/

CREATE OR REPLACE TYPE sedan_t AS OBJECT (
familycar ref familycar_t, 
cylinder_Size number(10)); 
/

CREATE TABLE familycar OF familycar_t (PRIMARY KEY (make,model)); 

現在我想爲「轎車」表設置主要如下。

CREATE TABLE sedan OF sedan_t (PRIMARY KEY (familycar_t.make,familycar_t.model)); 

但錯誤發生一樣，

Error starting at line : 4 in command - CREATE TABLE sedan OF sedan_t (PRIMARY KEY (familycar_t.make,familycar_t.model)) Error report - SQL Error: ORA-00904: "FAMILYCAR_T"."MAKE": invalid identifier 00904. 00000 - "%s: invalid identifier" *Cause:
*Action:

什麼是它的解決方案嗎？

Answer 1

使用引用的另一種方法是使用繼承：

CREATE OR REPLACE TYPE familycar_t AS OBJECT (
    make VARCHAR (10), 
    model VARCHAR(10), 
    year NUMBER (4), 
    fuel_type VARCHAR (10) 
) NOT FINAL; 
/

CREATE OR REPLACE TYPE sedan_t UNDER familycar_t (
    cylinder_Size number(10) 
); 
/

CREATE TABLE familycar OF familycar_t (PRIMARY KEY (make,model)); 

CREATE TABLE sedan OF sedan_t (PRIMARY KEY (make,model)); 

但是，你並不真正需要的​​表在這種情況下：

INSERT INTO familycar 
SELECT sedan_t('Ford', 'Model-T', 1908, 'Petrol', 4) FROM DUAL UNION ALL 
SELECT familycar_t('Ford', 'Model-A', 1903, 'Petrol') FROM DUAL; 

SELECT f.*, 
     TREAT(VALUE(f) AS sedan_t).cylinder_size AS cylinder_size 
FROM familycar f; 

輸出：

MAKE  MODEL   YEAR FUEL_TYPE CYLINDER_SIZE 
---------- ---------- ---------- ---------- ------------- 
Ford  Model-T   1908 Petrol     4 
Ford  Model-A   1903 Petrol   (null) 

Answer 2

您無法爲類型爲REF的屬性創建索引（請參閱here）。 如果REF的範圍有限，只能在REF屬性或列上定義索引。

CREATE OR REPLACE TYPE sedan_t AS OBJECT (
    familycar familycar_t, 
    cylinder_Size number(10) 
    ); 
/
CREATE TABLE sedan OF sedan_t (PRIMARY KEY (familycar.make, familycar.model)); 

Table SEDAN created.