126.Oracle数据库SQL开发之 数据库对象——PLSQL中使用对象
126.Oracle数据库SQL开发之 数据库对象——PLSQL中使用对象
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PLSQL中可以创建和操作对象。
看一个product_package 的包，如下：
CREATE PACKAGE product_package AS
TYPEt_ref_cursor IS REF CURSOR;
FUNCTIONget_products RETURN t_ref_cursor;
PROCEDUREdisplay_product(
p_id IN object_products.id%TYPE
);
PROCEDUREinsert_product(
p_id IN object_products.id%TYPE,
p_name IN object_products.name%TYPE,
p_description IN object_products.description%TYPE,
p_price INobject_products.price%TYPE,
p_days_valid IN object_products.days_valid%TYPE
);
PROCEDUREupdate_product_price(
p_id IN object_products.id%TYPE,
p_factor INNUMBER
);
FUNCTIONget_product(
p_id INobject_products.id%TYPE
) RETURNt_product;
PROCEDURE update_product(
p_productt_product
);
FUNCTIONget_product_ref(
p_id INobject_products.id%TYPE
) RETURN REFt_product;
PROCEDUREdelete_product(
p_id INobject_products.id%TYPE
);
END product_package;
/
1. Get_products函数
返回一个指向object_products表中对象的REF CURSOR。
2. Display_product过程
过程显示object_products表中单个对象的属性。
3. Insert_product过程
向object_products表中增加一个对象。
4. Update_product_price过程
更新object_products表中对象的price属性。
5. Get_product函数
返回object_products表的单个对象。
6. Update_product过程
更新object_products表中对象的所有属性。
7. Get_product_ref函数
返回对object_products表的单个对象的引用。
8. Delete_product过程
删除object_products表的单个对象。
9. Product_lifecycle2 过程
使用对象引用来访问产品。
10. 附件
CREATE PACKAGE BODY product_package AS
FUNCTIONget_products
RETURNt_ref_cursor IS
-- declarea t_ref_cursor object
v_products_ref_cursor t_ref_cursor;
BEGIN
-- get theREF CURSOR
OPENv_products_ref_cursor FOR
SELECTVALUE(op)
FROMobject_products op
ORDER BYop.id;
-- returnthe REF CURSOR
RETURNv_products_ref_cursor;
ENDget_products;
PROCEDUREdisplay_product(
p_id INobject_products.id%TYPE
) AS
-- declarea t_product object named v_product
v_productt_product;
BEGIN
-- attemptto get the product and store it in v_product
SELECTVALUE(op)
INTOv_product
FROMobject_products op
WHERE id =p_id;
-- displaythe attributes of v_product
DBMS_OUTPUT.PUT_LINE('v_product.id=' ||
v_product.id);
DBMS_OUTPUT.PUT_LINE('v_product.name=' ||
v_product.name);
DBMS_OUTPUT.PUT_LINE('v_product.description=' ||
v_product.description);
DBMS_OUTPUT.PUT_LINE('v_product.price=' ||
v_product.price);
DBMS_OUTPUT.PUT_LINE('v_product.days_valid=' ||
v_product.days_valid);
-- callv_product.get_sell_by_date() and display the date
DBMS_OUTPUT.PUT_LINE('Sell by date=' ||
v_product.get_sell_by_date());
ENDdisplay_product;
PROCEDUREinsert_product(
p_id IN object_products.id%TYPE,
p_name IN object_products.name%TYPE,
p_description IN object_products.description%TYPE,
p_price INobject_products.price%TYPE,
p_days_valid INobject_products.days_valid%TYPE
) AS
-- create at_product object named v_product
v_productt_product :=
t_product(
p_id,p_name, p_description, p_price, p_days_valid
);
BEGIN
-- addv_product to the object_products table
INSERT INTOobject_products VALUES (v_product);
COMMIT;
EXCEPTION
WHEN OTHERSTHEN
ROLLBACK;
END insert_product;
PROCEDUREupdate_product_price(
p_id IN object_products.id%TYPE,
p_factor INNUMBER
) AS
-- declarea t_product object named v_product
v_productt_product;
BEGIN
-- attemptto select the product for update and
-- storethe product in v_product
SELECTVALUE(op)
INTOv_product
FROMobject_products op
WHERE id =p_id
FOR UPDATE;
-- displaythe current price of v_product
DBMS_OUTPUT.PUT_LINE('v_product.price=' ||
v_product.price);
-- multiplyv_product.price by p_factor
v_product.price := v_product.price * p_factor;
DBMS_OUTPUT.PUT_LINE('New v_product.price=' ||
v_product.price);
-- updatethe product in the object_products table
UPDATE object_productsop
SET op =v_product
WHERE id =p_id;
COMMIT;
EXCEPTION
WHEN OTHERSTHEN
ROLLBACK;
ENDupdate_product_price;
FUNCTIONget_product(
p_id INobject_products.id%TYPE
)
RETURNt_product IS
-- declarea t_product object named v_product
v_productt_product;
BEGIN
-- get theproduct and store it in v_product
SELECTVALUE(op)
INTOv_product
FROM object_products op
WHERE op.id = p_id;
-- return v_product
RETURN v_product;
END get_product;
PROCEDURE update_product(
p_product IN t_product
) AS
BEGIN
-- update the product in theobject_products table
UPDATE object_products op
SET op = p_product
WHERE id = p_product.id;
COMMIT;
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END update_product;
FUNCTION get_product_ref(
p_id IN object_products.id%TYPE
)
RETURN REF t_product IS
-- declare a reference to a t_product
v_product_ref REF t_product;
BEGIN
-- get the REF for the product and
-- store it in v_product_ref
SELECT REF(op)
INTO v_product_ref
FROM object_products op
WHERE op.id = p_id;
-- return v_product_ref
RETURN v_product_ref;
END get_product_ref;
PROCEDURE delete_product(
p_id IN object_products.id%TYPE
) AS
BEGIN
-- delete the product
DELETE FROM object_products op
WHERE op.id = p_id;
COMMIT;
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END delete_product;
ENDproduct_package;
/
CREATEPROCEDURE product_lifecycle AS
-- declare object
v_product t_product;
BEGIN
-- insert a new product
product_package.insert_product(4, 'beef',
'25 lb pack of beef', 32, 10);
-- display the product
product_package.display_product(4);
-- get the new product and store it inv_product
SELECT product_package.get_product(4)
INTO v_product
FROM dual;
-- change some attributes of v_product
v_product.description := '20 lb pack ofbeef';
v_product.price := 36;
v_product.days_valid := 8;
-- update the product
product_package.update_product(v_product);
-- display the product
product_package.display_product(4);
-- delete the product
product_package.delete_product(4);
ENDproduct_lifecycle;
/
CREATEPROCEDURE product_lifecycle2 AS
-- declare object
v_product t_product;
-- declare object reference
v_product_ref REF t_product;
BEGIN
-- insert a new product
product_package.insert_product(4, 'beef',
'25 lb pack of beef', 32, 10);
-- display the product
product_package.display_product(4);
-- get the new product reference and store itin v_product_ref
SELECT product_package.get_product_ref(4)
INTO v_product_ref
FROM dual;
-- dereference v_product_ref using thefollowing query
SELECT DEREF(v_product_ref)
INTO v_product
FROM dual;
-- change some attributes of v_product
v_product.description := '20 lb pack ofbeef';
v_product.price := 36;
v_product.days_valid := 8;
-- update the product
product_package.update_product(v_product);
-- display the product
product_package.display_product(4);
-- delete the product
product_package.delete_product(4);
ENDproduct_lifecycle2;
/