来看oracle：
1 游标，游标的概念在我的理解是数组、是集合、是对象，但是他本身提供了遍历自己的方式
--控制语句 while
create or replace procedure pro_stu_0
as
cursor mycursor is select name,birs from stu;
v_name stu.name%type;
v_birs stu.birs%type;
begin
open mycursor;
fetch mycursor into v_name,v_birs;
while mycursor%found loop
dbms_output.put_line(v_name || v_birs);
fetch mycursor into v_name,v_birs;
end loop;
close mycursor;
end pro_stu_0;
--控制语句 loop
create or replace procedure pro_stu_1
as
cursor mycursor is select name,birs from stu;
v_name stu.name%type;
v_birs stu.birs%type;
begin
open mycursor ;
loop
fetch mycursor into v_name,v_birs;
exit when mycursor%notfound;
dbms_output.put_line(v_name||v_birs);
end loop;
close mycursor;
end pro_stu_1;
--控制语句for
create or replace procedure pro_stu_2
as
cursor mycursor is select name,birs from stu;
begin
for var_row in mycursor loop
dbms_output.put_line(var_row.name || var_row.birs);
end loop;
close mycursor;
end pro_stu_2;
--ref 游标（动态游标 loop循环）
create or replace procedure pro_stu_3
as
type mycursor is ref cursor ; --返回 行类型
v_cursor mycursor;
v_row stu%rowtype;
begin
open v_cursor for select * from stu where 1=1;--动态游标 在运行的时候解析参数 静态游标在编译的时候就确定了值
loop
exit when v_cursor%notfound;
fetch v_cursor into v_row;
dbms_output.put_line(v_row.name||v_row.birs);
end loop;
close v_cursor;
end pro_stu_3;
--ref 游标（动态游标 loop 循环 用游标变量接收）
create or replace procedure mypro as
type mytype_cursor is ref cursor;--声明弱类型游标 强类型：type mytype is ref cursor return emp%rowtype;指定了游标的类型
mycursor mytype_cursor; --定义变量
cursor mytype is select ename,empno from emp where 1 = 2;
myrow mytype%rowtype;--1、此处要有rowtype【游标接收】 定义接收数据的游标变量
-- type myrecord is record(ename emp.ename%type,empno emp.empno%type); --2 、复合变量接收
begin
open mycursor for select ename,empno from emp;
loop
fetch mycursor into myrow;
exit when mycursor%notfound;
dbms_output.put_line(myrow.ename || myrow.empno);
end loop;
close mycursor;
end mypro;
--ref 游标（动态游标 while 循环）
create or replace procedure proc_testCursor
as
type mycursor_type is ref cursor;
mycursor mycursor_type;
v_name emp.ename%type;
begin
open mycursor for select ename from emp;
while mycursor%found loop
fetch mycursor into v_name;
dbms_output.put_line(v_name);
fetch mycursor into v_name;
end loop;
end proc_testCursor;
--/*********ref 动态游标中好像不能用for 循环来遍历************/
解决方法：可以不用游标
create or replace procedure proc_testCursor
as
v_name emp.ename%type;
begin
for var_row in ( select ename,empno from emp) loop
dbms_output.put_line(var_row.ename||var_row.empno);
end loop;
end proc_testCursor;