--drop function top100cur(refcursor);
create function top100cur(refcursor) returns refcursor as $$
begin
	open $1 for select * from person limit 100;
	return $1;
end
$$language plpgsql;

----------测试游标---------
-- SELECT top100cur('abc');
-- fetch all from abc;

-- drop function from2cur(refcursor,int,int);
--这是一个返回游标中在一定范围内记录的函数--
create function from2cur(refcursor,int)returns setof text as $$
declare--声明一些下标变量
	pnam text;
	pno text;
	index int;
	lower int;
	upper int;
begin
	index:=1;
	lower:=$2;
	upper:=$3;
	
	fetch $1 into pnam,pno;--必须先fetch一条，否则found为false
	while found loop
		--只在[lower,upper]区间的记录才返回--
		if lower<=index and upper>=index then
			return next pnam||pno;
		end if;
		
		fetch $1 into pnam,pno;
		index:=index+1;

		--超过upper后，函数返回--
		if index>upper then 
			return;
		end if;
	end loop;
end
$$language plpgsql;

select top100cur('abc');--创建一个名字为abc的游标
-- fetch all in abc;--测试游标
select * from from2cur('abc',2,5);