Oracle TYPE OBJECT详解

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最近在自学PL/SQL高级编程，了解到对象类型（OBJECT TYPE）。

特意搜索了一下10G官方文档，下面不才基于此进行拓展：

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1. 介绍
Object-oriented programming is especially suited for building reusable components and complex

applications.

尤其适合于构建可重用的部件和复杂的应用程序的面向对象的编程。

In PL/SQL, object-oriented programming is based on object types.

在PL / SQL，面向对象的程序设计是基于对象类型。

They let you model real-world objects, separate interfaces and implementation details, and store
object-oriented data persistently in the database.
他们坚持让你模拟现实世界的对象，单独的接口和实现细节，面向对象的数据和存储在数据库中。

2. PL / SQL的声明和初始化对象
对象的类型可以代表任何真实世界的实体。例如，一个对象的类型可以代表一个学生，银行帐户，电脑屏幕上

，合理数量，或数据结构，如队列，堆栈，或列表。

CREATE OR REPLACE TYPE address_typ AS OBJECT (       street          VARCHAR2(30),                            city            VARCHAR2(20),       state           CHAR(2),                                   postal_code     VARCHAR2(6)          );

CREATE OR REPLACE TYPE employee_typ AS OBJECT(       employee_id       NUMBER(6),       first_name        VARCHAR2(20),       last_name         VARCHAR2(25),       email             VARCHAR2(25),       phone_number      VARCHAR2(25),       hire_date         DATE,       job_id            VARCHAR2(25),                                                          salary            NUMBER(8,2),                     commission_pct    NUMBER(2,2),                                                          manager_id        NUMBER(6),                                                          department_id     NUMBER(4),                                                          address           address_typ                                                          MAP MEMBER FUNCTION get_idno RETURN NUMBER,                                                          MEMBER PROCEDURE display_address(SELF IN OUT NOCOPY employee_typ)       );

--创建对象体

CREATE TYPE BODY employee_typ AS  MAP MEMBER FUNCTION get_idno RETURN NUMBER IS  BEGIN    RETURN employee_id;  END;  MEMBER PROCEDURE display_address ( SELF IN OUT NOCOPY employee_typ ) IS  BEGIN    DBMS_OUTPUT.PUT_LINE(first_name || ' '  || last_name);    DBMS_OUTPUT.PUT_LINE(address.street);    DBMS_OUTPUT.PUT_LINE(address.city || ', '  || address.state || ' ' ||                         address.postal_code);     END;END;

--持久化对象

CREATE TABLE employee_tab OF employee_typ;CREATE TYPE  emp_typ as table of employee_typ;

3. 在PL/SQL块中声明对象：

DECLARE  emp employee_typ; -- emp is atomically nullBEGIN-- call the constructor for employee_typ  emp := employee_typ(315, 'Francis', 'Logan', 'FLOGAN',        '555.777.2222', to_date('2012-12-24', 'yyyy-mm-dd'), 'SA_MAN', 11000, .15, 101, 110,         address_typ('376 Mission', 'San Francisco', 'CA', '94222'));  DBMS_OUTPUT.PUT_LINE(emp.first_name || ' ' || emp.last_name); -- display details  emp.display_address();  -- call object method to display detailsEND;

4. PL/SQL如何处理未初始化的对象：

DECLARE  emp employee_typ; -- emp is atomically nullBEGIN  IF emp IS NULL THEN DBMS_OUTPUT.PUT_LINE('emp is NULL #1'); END IF;  IF emp.employee_id IS NULL THEN     DBMS_OUTPUT.PUT_LINE('emp.employee_id is NULL #1');  END IF;  emp.employee_id := 330;  IF emp IS NULL THEN DBMS_OUTPUT.PUT_LINE('emp is NULL #2'); END IF;  IF emp.employee_id IS NULL THEN    DBMS_OUTPUT.PUT_LINE('emp.employee_id is NULL #2');  END IF;  emp := employee_typ(NULL, NULL, NULL, NULL,        NULL, NULL, NULL, NULL, NULL, NULL, NULL,         address_typ(NULL, NULL, NULL, NULL));  -- emp := NULL; -- this would have made the following IF statement TRUE  IF emp IS NULL THEN DBMS_OUTPUT.PUT_LINE('emp is NULL #3'); END IF;  IF emp.employee_id IS NULL THEN    DBMS_OUTPUT.PUT_LINE('emp.employee_id is NULL #3');  END IF;EXCEPTION   WHEN ACCESS_INTO_NULL THEN     DBMS_OUTPUT.PUT_LINE('Cannot assign value to NULL object');END;

5. 在PL/SQL中操纵对象：

5.1.调用对象构造器和方法（Calling Object Constructors and Methods）

DECLARE  emp employee_typ;BEGIN  INSERT INTO employee_tab VALUES (employee_typ(310, 'Evers', 'Boston', 'EBOSTON',   '555.111.2222', to_date('2012-12-24', 'yyyy-mm-dd'), 'SA_REP', 9000, .15, 101, 110,    address_typ('123 Main', 'San Francisco', 'CA', '94111')) );  INSERT INTO employee_tab VALUES (employee_typ(320, 'Martha', 'Dunn', 'MDUNN',    '555.111.3333', to_date('2012-11-5', 'yyyy-mm-dd'), 'AC_MGR', 12500, 0, 101, 110,    address_typ('123 Broadway', 'Redwood City', 'CA', '94065')) );END;

5.2 更新和删除对象：

DECLARE  emp employee_typ;BEGIN  INSERT INTO employee_tab VALUES (employee_typ(370, 'Robert', 'Myers', 'RMYERS',   '555.111.2277', to_date('2012-3-7', 'yyyy-mm-dd'), 'SA_REP', 8800, .12, 101, 110,    address_typ('540 Fillmore', 'San Francisco', 'CA', '94011')) );  UPDATE employee_tab e SET e.address.street = '1040 California'     WHERE e.employee_id = 370;  DELETE FROM employee_tab e WHERE e.employee_id = 310;END;

6. 通过REF修饰符操纵对象：

DECLARE  emp           employee_typ;  emp_ref   REF employee_typ;  emp_name      VARCHAR2(50);BEGIN  SELECT REF(e) INTO emp_ref FROM employee_tab e WHERE e.employee_id = 370;-- the following assignment raises an error, not allowed in PL/SQL-- emp_name := emp_ref.first_name || ' ' || emp_ref.last_name;-- emp := DEREF(emp_ref); not allowed, cannot use DEREF in procedural statements  SELECT DEREF(emp_ref) INTO emp FROM DUAL; -- use dummy table DUAL  emp_name := emp.first_name || ' ' || emp.last_name;  DBMS_OUTPUT.PUT_LINE(emp_name);END;

7. 定义相当于PL/SQL集合类型的SQL类型（Defining SQL Types Equivalent to PL/SQL Collection Types）

7.1 定义嵌套表：

--建嵌套表类型
CREATE TYPE CourseList AS TABLE OF VARCHAR2(10) -- define type
--建对象类型
CREATE TYPE student AS OBJECT ( -- create object
   id_num INTEGER(4),
   name    VARCHAR2(25),
   address VARCHAR2(35),
   status CHAR(2),
   courses CourseList); -- declare nested table as attribute
--建立嵌套表类型表
CREATE TABLE sophomores of student
NESTED TABLE courses STORE AS courses_nt;
--插入数据
insert into sophomores
values(1,'dylan','CARL STREET','ACTIVE',
       CourseList('MATH1020')
      );
--查询
SELECT a.*, b.*
from sophomores a, TABLE(a.courses) b;

select /*+ nested_table_get_refs */ *
from courses_nt t;

7.2 定义数组：
-- 声明数组类型（Each project has a 16-character code name）
-- We will store up to 50 projects at a time in a database column.
CREATE TYPE ProjectList AS VARRAY(50) OF VARCHAR2(16);
--创建表
CREATE TABLE dept_projects ( -- create database table
   dept_id NUMBER(2),
   name     VARCHAR2(15),
   budget   NUMBER(11,2),
-- Each department can have up to 50 projects.
   projects ProjectList);

--插入数据：
INSERT INTO dept_projects
    VALUES(60, 'Security', 750400,
      ProjectList('New Badges', 'Track Computers', 'Check Exits'));

8. 在动态SQL中使用对象：
8.1 定义对象类型person_typ和数组类型hobbies_var,并创建报TEAMS:

CREATE TYPE person_typ AS OBJECT (name VARCHAR2(25), age NUMBER);CREATE TYPE hobbies_var AS VARRAY(10) OF VARCHAR2(25);CREATE OR REPLACE PACKAGE teams   AUTHID CURRENT_USER AS   PROCEDURE create_table (tab_name VARCHAR2);   PROCEDURE insert_row (tab_name VARCHAR2, p person_typ, h hobbies_var);   PROCEDURE print_table (tab_name VARCHAR2);END;CREATE OR REPLACE PACKAGE BODY teams AS   PROCEDURE create_table (tab_name VARCHAR2) IS   BEGIN      EXECUTE IMMEDIATE 'CREATE TABLE ' || tab_name ||                        ' (pers person_typ, hobbs hobbies_var)';   END;   PROCEDURE insert_row (      tab_name VARCHAR2,      p person_typ,      h hobbies_var) IS   BEGIN      EXECUTE IMMEDIATE 'INSERT INTO ' || tab_name ||         ' VALUES (:1, :2)' USING p, h;   END;   PROCEDURE print_table (tab_name VARCHAR2) IS      TYPE  refcurtyp IS REF CURSOR;      v_cur refcurtyp;      p     person_typ;      h     hobbies_var;   BEGIN      OPEN v_cur FOR 'SELECT pers, hobbs FROM ' || tab_name;      LOOP         FETCH v_cur INTO p, h;         EXIT WHEN v_cur%NOTFOUND;         -- print attributes of 'p' and elements of 'h'         DBMS_OUTPUT.PUT_LINE('Name: ' || p.name || ' - Age: ' || p.age);         FOR i IN h.FIRST..h.LAST         LOOP           DBMS_OUTPUT.PUT_LINE('Hobby(' || i || '): ' || h(i));         END LOOP;      END LOOP;      CLOSE v_cur;   END;END;

8.2 调用TEAMS包中的存储过程：

DECLARE   team_name VARCHAR2(15);BEGIN   team_name := 'Notables';   TEAMS.create_table(team_name);   TEAMS.insert_row(team_name, person_typ('John', 31),      hobbies_var('skiing', 'coin collecting', 'tennis'));   TEAMS.insert_row(team_name, person_typ('Mary', 28),      hobbies_var('golf', 'quilting', 'rock climbing', 'fencing'));   TEAMS.print_table(team_name);END;

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output:
Name: John - Age: 31
Hobby(1): skiing
Hobby(2): coin collecting
Hobby(3): tennis
Name: Mary - Age: 28
Hobby(1): golf
Hobby(2): quilting
Hobby(3): rock climbing
Hobby(4): fencing

PL/SQL 过程已成功完成。

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