oracle游标，触发器

接plsql一文

--游标cursor，结果集上的指针

[sql]  

declare
  cursor c is
    select * from emp;--只是声明游标，还未取数据
  v_emp c%rowtype
begin
  open c;
  fetch c into v_emp;
  dbms_output.put_line(v_emp.ename);
  close c;
end;

declare
  cursor c is
    select * from emp;
  v_emp c%rowtype;
beigin
  open c;
  loop
    fetch c into v_emp;
    exit when (c%notfound);
    dbms_output.put_line(v_emp.ename);
  end loop;
  close c;
end;

--带参数的游标

[sql]  

declare
  cursor c(v_deptno emp.deptno%type,v_job emp.job%type)
  is
    select ename,sal from emp where deptno = v_deptno and job = v_job;
begin
  for v_temp in c(30,'clerk') loop
    dbms_output.put_line(v_temp.ename);
  end loop;
end;

 

--可更新的游标

[sql] 

declare
  cursor c
  is
    select * from emp2 for update;
begin
  for v_temp in c loop
    if(v_temp.sal < 2000) then
      update emp2 set sal = sal*2 where current of c;
    else if (v_temp.sal = 5000) then
      delete from emp2 where current of c;
    end if;
  end loop;
  commit;
end;

--创建存储过程，带有名字的PL/SQL块

[sql]  

grant create procedure to shijin;
create or replace procedure p
is
  cursor c is
    select * from emp2 for update;
begin
  for v_emp in c loop
    if(v_emp.deptno = 10) then
      update emp2 set sal = sal + 10 where current of c;
    else if (v_emp.deptno = 20) then
      update emp2 set sal = sal + 20 where current of c;
    else
      update emp2 set sal = sal + 50 where current of c;
    end if;
  end loop;
  commit;
end loop;

begin
  p;
end;
或者
exec p;

--带参数的存储过程，默认是in

[sql]  

create or replace procedure p
  (v_a in number,v_b number,v_ret out number,v_temp in out number)
is

begin
  if (v_a > v_b) then
    v_ret := v_a;
  else
    v_ret := v_b;
  end if;
  v_temp := v_temp + 1;
end;

declare
  v_a number := 3;
  v_b number := 4;
  v_ret number;
  v_temp number := 5;
begin
  p(v_a,v_b,v_ret,v_temp);
  dbms_output.put_line(v_ret);
  dbms_output.put_line(v_temp);
end;

--函数

[sql]  

create or replace function sal_tax
  (v_sal number)
  return number
is
begin
  if(v_sal < 2000) then
    return 0.10;
  elsif(v_sal < 2750) then
    return 0.15;
  else
    return 0.20;
  end if;
end;

select sal_tax(sal) from emp;

--触发器！！！！牢牢掌握概念

[sql]  

create table emp2_log
(
  uname varchar2(20),
  action varchar2(10),
  atime date
);
grant create triger to shijin;
create or replace trigger trig
  after insert or delete or update on emp2 --此处可以加上for each row
begin
  if inserting then
    insert into emp2_log values (USER,'insert',sysdate);
  elsif updating then
    insert into emp2_log values (USER,'update',sysdate);
  elsif deleting then
    insert into emp2_log values (USER,'delete',sysdate);
  end if;
end;

update emp2 set sal = sal*2 where deptno = 30;

drop trigger trig;

create or replace trigger trig
  after update on dept
  for each row
begin
  update emp set deptno = :NEW.deptno where deptno = :OLD.deptno;
end;

--树状结构数据的存储与显示

[sql]  

drop table article;

create table article
(
  id number primary key,
  cont varchar2(4000),
  pid number,
  isleaf number(1),--0代表非叶子节点，1代表叶子节点
  alevel number(2)
)

create or replace procedure p (v_pid article.pid%type,v_level binary_integer) is
  cursor c is select * from article where pid = v_pid;
  v_preStr varchar2(1024) := '';
begin
  for i in 1..v_level loop
    v_preStr := v_preStr || '****';
  end loop;
  for v_article in c loop
    dbms_output.put_line(v_preStr || v_article.cont);
    if(v_article.isleaf = 0) then
      p(v_articel.id,v_level + 1);
    end if;
  end loop;
end;
insert into article values (1,'蚂蚁大战大象',0,0,0);
insert into article values (2,'大象被打趴下',1,0,1);
insert into article values (3,'蚂蚁也不好过',2,1,2);
insert into article values (4,'瞎        说',2,0,2);
insert into article values (5,'没 有 瞎  说',4,1,3);
insert into article values (6,'怎 么 可  能',1,0,1);
insert into article values (7,'怎么没有可能',6,1,2);
insert into article values (8,'可能性很大的',6,1,2);
insert into article values (9,'大象进医院了',2,0,2);
insert into article values (10,'护士是蚂蚁',9,1,3);

begin
  p(0,0);
end;
show error;
--展示emp的树状结构