plsq程序设计--游标

游标属性：

notfound 未找到数据返回true

found    找到数据返回true

rowcount 游标当前位置

declare
--声明游标，这时数据库并没有真正去select数据
       cursor c is
              select * from emp;
        v_emp c%rowtype;
begin
--打开游标，此时执行select
        open c;
--执行fetch后，游标自动向下移动一条数据。没有循环，所以只取出第一条数据
             fetch c into v_emp;
             dbms_output.put_line(v_emp.ename);
        close c;
end;

循环取得游标内所有数据

declare
       cursor c is
              select * from emp;
        v_emp c%rowtype;
begin
        open c;
             loop
                     fetch c into v_emp;
             exit when (c%notfound);
                     dbms_output.put_line(c%rowcount);
                     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
                     dbms_output.put_line(c%rowcount);
                     dbms_output.put_line(v_emp.ename);
                     fetch c into v_emp;
             end loop;
        close c;
end;

declare
        cursor c is
               select * from emp;
begin
        for v_emp in c loop
            dbms_output.put_line(c%rowcount);
            dbms_output.put_line(v_emp.ename);
        end loop;
end;