oracle - 如何创建包含对象类型嵌套表的 Oracle 表？

Question

我有一个高度嵌套的对象类型结构，它允许我以树状方式保存数据。

我现在想创建一个表来缓存这些对象，但我很难创建表。我怀疑我的问题是多个嵌套级别，但不知道如何解决。

CREATE TYPE STEP_OBJ AS OBJECT (
  ID                        VARCHAR2(20),
  OTHER_FIELDS              VARCHAR2(100));
/

CREATE TYPE STEP_TAB_OBJ AS TABLE OF STEP_OBJ;
/

CREATE TYPE TREE_OBJ AS OBJECT (
  STEPS       STEP_TAB_OBJ,
  COMPLETE    VARCHAR2(1));
/

CREATE TYPE TABLE_OF_TREE_OBJ AS TABLE OF TREE_OBJ;
/

CREATE TABLE TREE_TABLE_CACHE (
   HANDLE               VARCHAR2(20),
   TABLE_OF_TREES       TABLE_OF_TREE_OBJ)
   NESTED TABLE TABLE_OF_TREES STORE AS TREE_TABLE_CACHE_OBJS;
/

CREATE TABLE TREE_TABLE_CACHE (
*
ERROR at line 1:
ORA-02320: failure in creating storage table for nested table column TABLE_OF_TREES
ORA-22913: must specify table name for nested table column or attribute

Oracle 11g。

Answer 1

您需要为内部集合指定一个存储子句。语法只是将嵌套集合的子句括在括号中，如下所示:

SQL> CREATE TABLE TREE_TABLE_CACHE (
  2     HANDLE               VARCHAR2(20),
  3     TABLE_OF_TREES       TABLE_OF_TREE_OBJ)
  4     NESTED TABLE TABLE_OF_TREES STORE AS TREE_TABLE_CACHE_OBJS
  5     ( NESTED TABLE STEPS          STORE AS TREE_TABLE_CACHE_STEPS)
  8   /

Table created.

SQL>