使用游标将emp表中的ename全取出来：

declare

cursor c is

select * from emp;

v_emp c%rowtype;

begin

open c;

loop --由于是一条一条fetch，所以使用do-while循环

fetch c into v_emp;

exit when(c%notfound);--这里是结束循环的条件

dbms_output.put_line(v_emp.ename);

end loop;

close c;

end;

/

declare

cursor c is

select * from emp;

v_emp c%rowtype;

begin

open c;

fetch c into v_emp;

while(c%found) loop--使用while-do循环

dbms_output.put_line(v_emp.ename);

fetch c into v_emp;

end loop;

end;

for循环的特点：（最不容易出错的循环，使用最多）

1. for里面变量不用声明

2. for里面游标不需open,不用fetch，不用close。它会帮你打开游标，从开头提取游标，关闭游标。

declare

cursor c is

select * from emp;

begin

for v_emp in c loop

dbms_output.put_line(v_emp.ename);

end loop;

end;

给游标传递形参：

declare

cursor c(v_deptno emp.deptno%type,v_job emp.job%type) is --定义两个形参

select ename,sal from emp where deptno = v_deptno and job = v_job;

begin

for v_emp in c(30，’clerk’) loop --传递给形参两个参数值

dbms_output.put_line(v_emp.ename);

end loop;

end;

定义用于更新的游标：

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;--游标走哪更新到哪

elsif （v_temp.sal = 5000） then

delete fom emp2 where current of c;

end if;

end loop;

commit;

end;