Oracle11G-SQL开发指南-11-PL/SQL编程。
1. 块结构
[DECLARE declaration_statements ]BEGIN
executable_statements
[EXCEPTIONexception_handling_statements
]
END;
例1：
DECLARE
V_WIDTH INTEGER;
V_HEIGHT INTEGER := 3;
V_ARE INTEGER := 6;
BEGIN
V_WIDTH := V_ARE / V_HEIGHT;
DBMS_OUTPUT.PUT_LINE('v_width=' || V_WIDTH);
EXCEPTION
WHEN ZERO_DIVIDE THEN
DBMS_OUTPUT.PUT_LINE('报错了：Division by zero');
END;
2. 变量和类型
变量在DECLARE块中声明;
声明时要同时包含名称和类型;
v_id INTEGER;
v_char VARCHAR2(50);
v_type table_name.colmnt_name%TYPE;
3. 条件逻辑
IF、THEN、ELSE、ELSEIF、ENDIF;
4. 循环
a> 简单循环
LOOP
statements
END LOOP;
结束循环要使用EXIT或EXIT WHEN语句
结束当前循环进行下一次循环可以使用CONTINUE或CONTINUE WHEN语句
b> WHILE循环
WHILE condition LOOP
statements
END LOOP;
c> FOR循环
FOR loop_variable IN [REVERSE] lower_bound.. upper_bound LOOPstatements
END LOOP;
5. 游标cursor
a> 声明变量，用于存储记录的列值;
b> 声明游标;
c> 打开游标;
d> 一次从游标中取出一个值来，并将列值存储在第1步声明的变量中，进行自定义的操作处理;
e> 关闭游标;
6. 异常 exception 块中的内容
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('出现异常：Division by zero');
ROLLBACK;
RETURN;
7. 过程 : 一组SQL和pl/sql语句
a> 创建过程
CREATE [ OR REPLACE ] PROCEDURE pocedure_name[(parameter_name [IN | OUT | IN OUT ] type [, ...])]
{IS | AS }
BEGIN
procedure_body
END pocedure_name ;
b> 调用过程:
call pocedure_name (parameter_name => value);
c> 获取过程信息 user_procedures
d> 删除过程 drop PROCEDURE pocedure_name ;
e> 查看报错 show errors
8. 函数，与过程相似，就是多一个返回值
a> 创建函数
CREATE [ OR REPLACE ] FUNCTION function_name[(parameter_name [IN | OUT | IN OUT ] type [, ...])]
RETURN type
{IS | AS }
BEGIN
function_body
END function_name ;
b> 调用函数:与内置函数类似
c> 获取函数信息 user_procedures
d> 删除过程 drop FUNCTION function_name ;
9. 包，把函数和过程组织在一起
包由两部分组成：规范specification和包体body
创建包规范：
CREATE [OR REPLACE ] PACKAGE package_name{IS | AS}
package_specification
END package_name ;
创建包体：
CREATE [OR REPLACE ] PACKAGE BODY package_name{IS | AS}
package_body
END package_name;
10. 触发器
CREATE [OR REPLACE] TRIGGER trigger_name{BEFORE | ALTER | INSTEAD OF | FOR } trigger_event
ON table_name
[FOR EACH ROW][{FORWARD | REVERSE} CROSSEDITION ]
[{FOLLOWS | PRECEDES} schema.other_trigger]
[{ENABLE | DISABLE}]
[WHEN trigger_condition ]
BEGIN
trigger_body;
END trigger_name ;
创建时的is与as区别
是ORACLE为了方便而设置的同义词
在存储过程(PROCEDURE)和函数(FUNCTION)中没有区别;
在视图(VIEW)中只能用AS不能用IS;
在游标(CURSOR)中只能用IS不能用AS。
-------------------------------------------------------
-- 块 声明块，执行块，异常块
DECLARE
V_WIDTH INTEGER;
V_HEIGHT INTEGER := 3;
V_ARE INTEGER := 6;
BEGIN
V_WIDTH := V_ARE / V_HEIGHT;
DBMS_OUTPUT.PUT_LINE('v_width=' || V_WIDTH);
EXCEPTION
WHEN ZERO_DIVIDE THEN
DBMS_OUTPUT.PUT_LINE('报错了：Division by zero');
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('出现异常：Division by zero');
END;
-------------------------------------------------------
--简单循环 ，IF，EXIT WHEN
DECLARE
V_COUNT INTEGER := 0;
BEGIN
LOOP
V_COUNT := V_COUNT + 1;
IF V_COUNT = 3 THEN
CONTINUE;
END IF;
DBMS_OUTPUT.PUT_LINE('当前值为：' || v_count);
EXIT WHEN V_COUNT = 5;
END LOOP;
END;
-------------------------------------------------------
--简单循环，CONTINUE WHEN，EXIT WHEN
DECLARE
V_COUNT INTEGER := 0;
BEGIN
LOOP
V_COUNT := V_COUNT + 1;
CONTINUE WHEN v_count = 3 ;
DBMS_OUTPUT.PUT_LINE('当前值为：' || v_count);
EXIT WHEN V_COUNT = 5;
END LOOP;
END;
-------------------------------------------------------
-- while 循环
DECLARE
V_COUNT INTEGER := 0;
BEGIN
WHILE V_COUNT < 6 LOOP
V_COUNT := V_COUNT + 1;
DBMS_OUTPUT.PUT_LINE('当前值为：' || V_COUNT);
END LOOP;
END;
-------------------------------------------------------
--for循环
DECLARE
V_COUNT INTEGER := 0;
BEGIN
FOR V_COUNT IN 1.. 6 LOOP
DBMS_OUTPUT.PUT_LINE('当前值为：' || V_COUNT);
END LOOP;
END;
-------------------------------------------------------
-- 游标示例1 完整过程
DECLARE
-- 1：声明变量
V_PRODUCT_ID PRODUCTS.PRODUCT_ID%TYPE;
V_NAME PRODUCTS.NAME%TYPE;
V_PRICE PRODUCTS.PRICE%TYPE;
-- 2：声明游标
CURSOR V_PRODUCT_CURSOR IS
SELECT PRODUCT_ID, NAME, PRICE FROM PRODUCTS ORDER BY PRODUCT_ID;
BEGIN
-- 3： 打开游标
OPEN V_PRODUCT_CURSOR;
LOOP
-- 4： 从游标中取数据
FETCH V_PRODUCT_CURSOR
INTO V_PRODUCT_ID, V_NAME, V_PRICE;
EXIT WHEN V_PRODUCT_CURSOR%NOTFOUND;
DBMS_OUTPUT.PUT_LINE('id值为：' || V_PRODUCT_ID || 'name=：' || V_NAME);
END LOOP;
-- 5.关闭游标
CLOSE V_PRODUCT_CURSOR;
END;
-------------------------------------------------------
-- 游标示例2 ： 结合for循环 不用显示打开和关闭游标
DECLARE
-- 1：声明变量
-- 2：声明游标
CURSOR V_PRODUCT_CURSOR IS
SELECT PRODUCT_ID, NAME, PRICE FROM PRODUCTS ORDER BY PRODUCT_ID;
BEGIN
-- 3： 打开游标
FOR v_product IN V_PRODUCT_CURSOR LOOP
-- 4： 从游标中取数据
DBMS_OUTPUT.PUT_LINE('id值为：' ||v_product.PRODUCT_ID || 'name=：' || v_product.NAME);
END LOOP;
-- 5.关闭游标
END;
-------------------------------------------------------
-- 游标示例3 ：ref cursor游标 结合open-for语句 灵活使用游标
-- 动态关联结果集的临时对象。即在运行的时候动态决定执行查询。
DECLARE
-- 1：声明变量
-- 2：声明游标
TYPE T_PRODUCT_CURSOR IS REF CURSOR RETURN PRODUCTS%ROWTYPE;
V_PRODUCT_CURSOR T_PRODUCT_CURSOR;
V_PRODUCT PRODUCTS%ROWTYPE;
BEGIN
-- 3： 打开游标
OPEN V_PRODUCT_CURSOR FOR
SELECT * FROM PRODUCTS WHERE PRODUCT_ID < 5;
LOOP
FETCH V_PRODUCT_CURSOR INTO V_PRODUCT;
EXIT WHEN V_PRODUCT_CURSOR%NOTFOUND;
-- 4： 从游标中取数据
DBMS_OUTPUT.PUT_LINE('id值为：'|| V_PRODUCT.PRODUCT_ID || 'name=：'||V_PRODUCT.NAME);
END LOOP;
-- 5.关闭游标
CLOSE V_PRODUCT_CURSOR;
END;
-------------------------------------------------------
-- 游标示例4 无约束游标
DECLARE
TYPE T_CURSOR IS REF CURSOR; --先定义动态游标
V_CURSOR T_CURSOR;
V_PRODUCT PRODUCTS%ROWTYPE;
V_CUSTOMER CUSTOMERS%ROWTYPE;
BEGIN
OPEN V_CURSOR FOR
SELECT * FROM PRODUCTS WHERE PRODUCT_ID < 5 ;
LOOP
FETCH V_CURSOR INTO V_PRODUCT; -- 第一次动态使用
EXIT WHEN V_CURSOR%NOTFOUND;
DBMS_OUTPUT.PUT_LINE('id值为：' || V_PRODUCT.PRODUCT_ID || 'name=：' || V_PRODUCT.NAME);
END LOOP;
OPEN V_CURSOR FOR
SELECT * FROM CUSTOMERS WHERE CUSTOMER_ID <3 ;
LOOP
FETCH V_CURSOR INTO V_CUSTOMER; -- 第二次动态使用
EXIT WHEN V_CURSOR%NOTFOUND;
DBMS_OUTPUT.PUT_LINE('id值为：' || V_CUSTOMER.customer_ID || 'name=：' || V_CUSTOMER.first_name);
END LOOP;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('出现异常：Division by zero');
CLOSE V_CURSOR;
END;
-------------------------------------------------------
-- 过程
CREATE OR REPLACE PROCEDURE update_product_price(
p_product_id IN products.product_id%TYPE,
p_factor IN NUMBER
) AS
v_product_count INTEGER;
BEGIN
-- count the number of products with the
-- supplied product_id (will be 1 if the product exists)
SELECT COUNT(*)
INTO v_product_count
FROM products
WHERE product_id = p_product_id;
-- if the product exists (v_product_count = 1) then
-- update that product's price
IF v_product_count = 1 THEN
UPDATE products
SET price = price * p_factor
WHERE product_id = p_product_id;
COMMIT;
END IF;
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END update_product_price;
-------------------------------------------------------
-- 函数1
CREATE OR REPLACE FUNCTION circle_area (
p_radius IN NUMBER
) RETURN NUMBER AS
v_pi NUMBER := 3.1415926;
v_area NUMBER;
BEGIN
-- circle area is pi multiplied by the radius squared
v_area := v_pi * POWER(p_radius, 2);
RETURN v_area;
END circle_area;
-- 函数2
CREATE OR REPLACE FUNCTION average_product_price (
p_product_type_id IN INTEGER
) RETURN NUMBER AS
v_average_product_price NUMBER;
BEGIN
SELECT AVG(price)
INTO v_average_product_price
FROM products
WHERE product_type_id = p_product_type_id;
RETURN v_average_product_price;
END average_product_price;
-------------------------------------------------------
-- 包
CREATE OR REPLACE PACKAGE product_package AS
TYPE t_ref_cursor IS REF CURSOR;
FUNCTION get_products_ref_cursor RETURN t_ref_cursor;
PROCEDURE update_product_price (
p_product_id IN products.product_id%TYPE,
p_factor IN NUMBER
);
END product_package;
-------------------------------------------------------
-- 触发器
CREATE OR REPLACE TRIGGER before_product_price_update
BEFORE UPDATE OF price
ON products
FOR EACH ROW
when (new.price < old.price * 0.75)
BEGIN
dbms_output.put_line('product_id = ' || :old.product_id);
dbms_output.put_line('Old price = ' || :old.price);
dbms_output.put_line('New price = ' || :new.price);
dbms_output.put_line('The price reduction is more than 25%');
-- insert row into the product_price_audit table
INSERT INTO product_price_audit (
product_id, old_price, new_price
) VALUES (
:old.product_id, :old.price, :new.price
);
END before_product_price_update;