--演示隐式游标,系统自动声明，自动打开，自动使用并且自动关闭
begin
update emp set sal = 1000;
dbms_output.put_line('影响的行数：' || sql%rowcount);
end;
rollback;
/*游标的使用方法：
第一步：声明游标
第二步：打开游标
第三步：使用游标进行循环操作
第四步：关闭游标*/
--普通游标，游标本身就是一个变量
declare
--下面的这行代码声明了一个游标
cursor mycur is select * from emp where deptno = 20;
emprow emp%rowtype;
begin
open mycur; --打开游标
loop
fetch mycur into emprow; --把游标所指的纪录放到变量中
exit when (mycur%notfound); --当游标没有指向行时退出循环
dbms_output.put_line('名字：' || emprow.ename || '薪水：' || emprow.sal);
end loop;
close mycur; --关闭游标
end;
--简单游标，列操作
declare
empname emp.ename%type;
empsal emp.sal%type;
cursor mycur is select ename,sal from emp where deptno = 30;
begin
open mycur;
loop
fetch mycur into empname,empsal;
exit when mycur%notfound;
dbms_output.put_line('姓名:' || empname || '工资' || empsal);
end loop;
end;
--简单游标，列操作
declare
cursor c
is
select * from dept;
vDept_row_record c%rowtype;
begin
open c;
fetch c into vDept_row_record;
dbms_output.put_line(vDept_row_record.dname);
close c;
end;
--when循环游标
declare
cursor c
is
select * from dept;
vDept_row_record c%rowtype;
begin
open c;
loop
fetch c into vDept_row_record;
exit when(c%notfound);
dbms_output.put_line(vDept_row_record.dname);
end loop;
close c;
end;
--while循环游标
declare
cursor c
is
select * from dept;
vDept_row_record c%rowtype;
begin
open c;
fetch c into vDept_row_record;
while (c%found) loop
dbms_output.put_line(vDept_row_record.dname);
fetch c into vDept_row_record;
end loop;
close c;
end;
--for循环游标
declare
cursor c
is
select * from dept;
vDept_row_record c%rowtype;
begin
for vDept_row_record in c loop
dbms_output.put_line(vDept_row_record.dname);
end loop;
end;
--带参游标
declare
cursor c(sSal emp.sal%type, sEmpno emp.empno%type)
is
select * from emp where sal >= sSal and empno > sEmpno;
begin
for record_data in c(2500, 6666) loop
dbms_output.put_line(record_data.ename);
end loop;
end;
--update游标
declare
cursor c(sSal emp2.sal%type)
is
select * from emp2 where sal >= sSal for update;
begin
for record_data in c(2500) loop
if (record_data.sal < 3000) then
update emp2 set sal = sal + 3 where current of c;
dbms_output.put_line(record_data.ename);
elsif (record_data.sal = 5000) then
update emp2 set sal = sal - 3 where current of c;
dbms_output.put_line(record_data.ename);
end if;
end loop;
end;
--引用游标不能使用循环游标的语法
--引用游标不能进行删除和修改
--引用游标是一个数据类型，使用该类型必须声明变量
--弱类型引用游标，就是不指定游标将要提取的数据行的类型
declare
type my_cur_type is ref cursor;
mycur my_cur_type;--声明变量
which varchar2(10);
deptrow dept%rowtype;
emprow emp%rowtype;
begin
which := '&请选择dept还是emp';
if (which = 'dept') then
open mycur for select * from dept;
loop
fetch mycur into deptrow;
exit when (mycur%notfound);
dbms_output.put_line(deptrow.deptno || ' ' || deptrow.dname);
end loop;
elsif (which = 'emp') then
open mycur for select * from emp;
loop
fetch mycur into emprow;
exit when (mycur%notfound);
dbms_output.put_line(emprow.empno || ' ' || emprow.ename);
end loop;
end if;
close mycur;
end;
--强类型引用游标，就是指定游标将要提取的数据行的类型 ，只能是record或%rowtype类型
--比如：return number是错的，return emp.ename%type也是错的
declare
type mycurtype is ref cursor return emp%rowtype;
mycur mycurtype;--声明变量
emprow emp%rowtype;
begin
open mycur for select * from emp;
loop
fetch mycur into emprow;
exit when mycur%notfound;
dbms_output.put_line(emprow.empno || ' ' || emprow.ename);
end loop;
close mycur;
end;
