游标

begin
insert into userroles values (55,'aa');
end;

begin
update userroles set name='bb' where id=55;
end;

begin
delete from userroles where id=55;
end;

declare
r userroles%rowtype;
begin
select * into r from userroles where id=2;
dbms_output.put_line(r.id||','||r.name);
end;



declare
a int;
begin
delete from books where lower(title) like 'java%';
a:=sql%rowcount;--sql隐式游标
rollback;
dbms_output.put_line('删除了'||a||'条记录');
end;


--显式游标

declare
cursor cur is select * from books where rownum<=50;--1.定义游标
bk books%rowtype;
begin
open cur;--2.打开游标
loop
exit when cur%notfound;
fetch cur into bk;--3.从游标中提取数据
dbms_output.put_line(bk.id||' '||bk.title);
--dbms_output.put_line(cur%rowcount);
end loop;
close cur;--4.关闭游标
end;

--显式游标
--带参
declare
cursor cur(cnt int) is select * from books where rownum<=cnt;--1.定义游标
bk books%rowtype;
begin
open cur(20);--2.打开游标传入参数
loop
exit when cur%notfound;
fetch cur into bk;--3.从游标中提取数据
dbms_output.put_line(bk.id||' '||bk.title);
--dbms_output.put_line(cur%rowcount);
end loop;
close cur;--4.关闭游标
end;




declare
cursor cur(cnt int,bn varchar) is
select * from books where
lower(title) like bn and rownum<=cnt;--1.定义游标
bk books%rowtype;
begin
open cur(20,'java%');--2.打开游标
loop
exit when cur%notfound;
fetch cur into bk;--3.从游标中提取数据
dbms_output.put_line(bk.id||' '||bk.title);
--dbms_output.put_line(cur%rowcount);
end loop;
close cur;--4.关闭游标
end;

--基于游标的更新
declare
cursor cur(cnt int,bn varchar) is
select * from books where
lower(title) like bn and rownum<=cnt
for update;--1.定义游标
bk books%rowtype;
begin
open cur(20,'java%');--2.打开游标
loop
exit when cur%notfound;
fetch cur into bk;--3.从游标中提取数据
dbms_output.put_line(bk.id||' '||bk.title||' '||bk.unitprice);
if bk.unitprice<50 then
update books set unitprice=unitprice+5 where current of cur;
end if;
end loop;
close cur;--4.关闭游标
end;

--for游标
declare
cursor cur is select id,title from books where rownum<=50;
begin
for bk in cur
loop
dbms_output.put_line(bk.id||' '||bk.title);
end loop;
end;

--ref游标(动态游标)
declare
type MyCur is ref cursor;--定义一种类型
cur MyCur;
bk books%rowtype;
rl userroles%rowtype;
begin
open cur for 'select * from books where rownum<=50';
loop
fetch cur into bk;
exit when cur%notfound;
dbms_output.put_line(bk.id||' '||bk.title);
end loop;
close cur;
open cur for 'select * from userroles';
loop
fetch cur into rl;
exit when cur%notfound;
dbms_output.put_line(rl.id||' '||rl.name);
end loop;
close cur;
end;