oracle触发器及异常处理 简单例子

create sequence person_seq
start with 1
increment by 1
order                     --按顺序
nocycle                 --不循环不重复
;



insert into person values(person_seq.nextval,null,'iteye);
delete from person;
update person set user_name ='zwllxs6' where id = 3;

---触发器
create or replace trigger person_tr before insert or update or delete on person
for each row
Declare
   can_not_update_exception  EXCEPTION;

begin

    dbms_output.put_line('testest');
    if inserting then
       dbms_output.put_line('inserting');
    end if;
    if updating then
       dbms_output.put_line('updating');
       dbms_output.put_line('old: '||:old.user_name);
       dbms_output.put_line('new: '||:new.user_name);
       if(:old.user_name<>:new.user_name) then
          dbms_output.put_line('不一样，不能更新');
         Raise_application_error(-20000,'不一样，不能更新');
       end if;

    end if;
    if deleting then
       dbms_output.put_line('deleting');
    end if;
end;

Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:orcl", "scott", "******");

            // 创建状态
            Statement stmt = conn.createStatement();
            // 执行SQL语句，返回结果集
            ResultSet rs = stmt.executeQuery("SELECT * FROM person");
            while (rs.next()) {
                int id = rs.getInt("id");
                String userName = rs.getString("user_name");
                System.out.println("id: "+id);
                System.out.println("userName: "+userName);
            }

            int num=stmt.executeUpdate("update person set user_name ='zwllxs5' where id = 3");
            System.out.println("num: "+num);