求解答，v_sql 为什么一直是null解决方法

select 'SELECT count(*) FROM ' || t.table_name ||
  ' WHERE LOGDATE >= :i_BeginDate AND LOGDATE < :i_EndDate'
  from sys.user_all_tables t
  where t.table_name like '%T_TEMPLATE%'
  AND T.table_name NOT LIKE '%APPLY%'
  AND T.table_name NOT LIKE '%HISTRY%'

------解决方案--------------------

create or replace function f_fw_Information(i_BeginDate date,
 i_EndDate date) return number as
 v_sql VARCHAR2(200);
 v_exesql VARCHAR2(200);
 sumc number;
 type o_cursor is ref cursor;
 c1 o_cursor;
begin
 sumc := 0;
 v_sql := 'select ''SELECT count(*) FROM '' || t.table_name ||
 '' WHERE LOGDATE >= :i_BeginDate AND LOGDATE < :i_EndDate''
 from sys.user_all_tables t
 where t.table_name like ''%T_TEMPLATE%''
 AND T.table_name NOT LIKE ''%APPLY%''
 AND T.table_name NOT LIKE ''%HISTRY%''';
 OPEN c1 for v_sql;
 LOOP
 FETCH c1
 INTO v_exesql;
 EXIT WHEN c1%NOTFOUND;--移上来试试呢
 execute immediate v_exesql  into sumc  
 using i_BeginDate, i_EndDate;
 --EXIT WHEN c1%NOTFOUND;
 sumc := sumc + sumc;
 END LOOP;
 CLOSE c1;
 return sumc;
exception
 WHEN OTHERS THEN
 return 0;
end f_fw_Information;