游标有关问题_Oracle管理

游标问题
定义一个游标获取数据集，但是数据集是有条件的，例如
if a=1 then
select .....
else
select ....
end if

该怎么写，谢谢！

------解决方案--------------------

SQL code

SQL> create or replace procedure proc_test_cursor(i_num number,o_cur out sys_refcursor)  2  as  3  begin  4   if i_num=1 then  5      open o_cur for select 1 from dual;  6    else  7     open o_cur for select empno from emp where empno=7369;  8    end if;  9  end; 10  /Procedure created.SQL> var v_cur refcursorSQL> exec proc_test_cursor(1,:v_cur);PL/SQL procedure successfully completed.SQL> print v_cur         1----------         1SQL> exec proc_test_cursor(2,:v_cur);PL/SQL procedure successfully completed.SQL> print v_cur     EMPNO----------      7369SQL>
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SQL codeSQL> var v_cur refcursorSQL> create or replace procedure proc_test_cursor(o_cur out sys_refcursor)  2  as  3  cv_cur1 sys_refcursor;  4  v_empno number(10);  5  begin  6   open cv_cur1 for select empno from emp;  7   loop  8   fetch cv_cur1 into v_empno;  9   exit when cv_cur1%notfound; 10   exit when o_cur%isopen; 11    if v_empno=7934 then 12      open o_cur for select 1 from dual; 13    end if; 14   end loop; 15   close cv_cur1; 16  end; 17  /Procedure created.SQL> exec proc_test_cursor(:v_cur);PL/SQL procedure successfully completed.SQL> print v_cur         1----------         1SQL>
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探讨
我想在cur_mult_fab 里加if语句。请问如何修改。谢谢
DECLARE
  CURSOR cur_mult_fab is
  select * from ...
 begin
  FOR mult_fab_rec IN cur_mult_fab
  LOOP
  BEGIN
  .....
  END;
  END LOOP;
 end;

------解决方案--------------------
SQL codeSQL> declare  2  cursor cv_1 is  select empno from emp;  3  v_num number(10);  4  begin  5   for ccc in cv_1  6   loop  7   dbms_output.put_line(ccc.empno);  8   end loop;  9  end; 10  / 73697499752175667654769877827788783978447876790079027934 PL/SQL procedure successfully completed SQL>