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PL/SQL基础-异常处理

Jun 07, 2016 pm 04:08 PM

ORACLE异常分为两种类型:系统异常、自定义异常。 其中系统异常又分为:预定义异常和非预定义异常。1.预定义异常ORACLE定义了他们

异常处理
一、异常的类型
Oracle异常分为两种类型:系统异常、自定义异常。
 其中系统异常又分为:预定义异常和非预定义异常。
1.预定义异常
ORACLE定义了他们的错误编号和异常名字,常见的预定义异常处理Oracle常见的错误

NO_DATA_FOUND SELECT ... INTO ... 时,没有找到数据
DUL_VAL_ON_INDEX 试图在一个有惟一性约束的列上存储重复值
CURSOR_ALREADY_OPEN 试图打开一个已经打开的游标
TOO_MANY_ROWS SELECT ... INTO ... 时,查询的结果是多值
ZERO_DIVIDE 零被整除
2.非预定义异常
ORACLE为它定义了错误编号,但没有定义异常名字。我们使用的时候,先声名一个异常名,
 通过伪过程PRAGMA EXCEPTION_INIT,将异常名与错误号关联起来。

3.自定义异常
 程序员从我们业务角度出发,制定的一些规则和限制。
二、异常处理
PL/SQL中,异常处理按个步骤进行:
 定义异常
 抛出异常
 捕获及处理异常

a.定义异常

exception_name EXCEPTION;

b.抛出异常

RAISE exception_name

c.捕获及处理异常

EXCEPTION
WHEN e_name1 [OR e_name2 ... ] THEN
statements;
WHEN e_name3 [OR e_name4 ... ] THEN
statements;
......
WHEN OTHERS THEN
statements;
END;

--使用预定义的异常
--根据用记输入的商品ID来查商品库存

DECLARE
V_ID ES_PRODUCT.ID%TYPE := &V_ID; --用户输入商品ID
V_STOCKCOUNT ES_PRODUCT.STOCKCOUNT%TYPE; ---库存量
BEGIN
SELECT STOCKCOUNT INTO V_STOCKCOUNT FROM ES_PRODUCT WHERE ID = V_ID;
DBMS_OUTPUT.PUT_LINE('库存量:' || V_STOCKCOUNT);
--判断库存量是否正常
IF V_STOCKCOUNT > 0 THEN
--更新库存,一次买一个减掉一个
UPDATE ES_PRODUCT
SET STOCKCOUNT = STOCKCOUNT - 1
--更新指定的,不然会全部更新
WHERE ID = V_ID;
--提出数据操作
COMMIT;
DBMS_OUTPUT.PUT_LINE('库存更新成功');
ELSIF V_STOCKCOUNT = 0 THEN
DBMS_OUTPUT.PUT_LINE('库存量是0,,没有库存了');
ELSE
DBMS_OUTPUT.PUT_LINE('库存异常');
END IF;
EXCEPTION
WHEN NO_DATA_FOUND THEN
DBMS_OUTPUT.PUT_LINE('该商品不存在!');
ROLLBACK;
WHEN TOO_MANY_ROWS THEN
DBMS_OUTPUT.PUT_LINE('该商品存在多个!');
ROLLBACK;
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('发生了其它错误!');
ROLLBACK;
END;

 


--自定义异常
--实现订单删除

 

SELECT * FROM ES_ORDER;
DECLARE
E_NO_RESULT EXCEPTION;
V_ID ES_ORDER.ID%TYPE := &ID;
V_EXCEPTION1 CONSTANT VARCHAR2(50) := '删除数据不成功!';
V_EXCEPTION2 CONSTANT VARCHAR2(50) := '发生了错误!';
BEGIN
DELETE FROM ES_ORDER WHERE ID = V_ID;
IF (SQL%NOTFOUND) THEN
--删除没有执行
RAISE E_NO_RESULT;
END IF;
EXCEPTION
WHEN E_NO_RESULT THEN
DBMS_OUTPUT.PUT_LINE(V_EXCEPTION1);
ROLLBACK;
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE(V_EXCEPTION2);
ROLLBACK;
END;

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