CREATE OR REPLACE PROCEDURE ss(eff_day VARCHAR2)

-- eff_day 统计日期，格式为 'yyyymmdd'

AS

v_year        INTEGER;

v_month INTEGER;

v_day        INTEGER;

v_date  DATE;

v_tmpDate DATE;

v_count INTEGER;

v_begin INTEGER;

v_eff_date VARCHAR2(12);

BEGIN

v_eff_date := TO_CHAR(TO_DATE(eff_day,'yyyymmdd')-1,'yyyymmdd');

v_year := TO_NUMBER(SUBSTR(v_eff_date,1,4));

v_month := TO_NUMBER(SUBSTR(v_eff_date,5,2));

v_day := TO_NUMBER(SUBSTR(v_eff_date,7,2));

v_date := to_date(v_eff_date,'yyyymmdd'); -- 时段的起始时间

v_begin := 0;

FOR v_count IN 1..24   -- 一天24时段，循环24次

LOOP

INSERT INTO a_contentbyper_7_1(icp_id,channel_id,content_id,area_code,year, month,day,time_id,itemclass,itemvalue)

(SELECT /*+  INDEX(A I_CREATED_T_EVENT_T) index(a I_CREATED_T_EVENT_T) index(a I_EVENT_ID) use_nl(a c)*/ a.icp_account_id,-1,b.id,1,1,1,1,

1 - 1,2,sum(c.amount) FROM mid.event_t a,content_t b,mid.event_resimpact_t c

WHERE a.itemname = b.name AND c.event_id = a.id AND c.dest_res_name = 'RMB Yuan'

AND a.created_t >= TO_DATE('20030716','YYYYMMDD') AND a.created_t < TO_DATE('20030716','YYYYMMDD') + 1/24

GROUP BY a.icp_account_id,b.id);

insert into log_date values (sysdate,v_count);

COMMIT;

INSERT INTO a_contentbyper_7_1(icp_id,channel_id,content_id,area_code,year, month,day,time_id,itemclass,itemvalue)

(SELECT /*+  INDEX(A I_CREATED_T_EVENT_T) index(a I_CREATED_T_EVENT_T) index(a I_EVENT_ID) use_nl(a c)*/ a.icp_account_id,-1,b.id,1,1,1,1,

1 - 1,2,sum(c.amount) FROM mid.event_t a,content_t b,mid.event_resimpact_t c

WHERE a.itemname = b.name AND c.event_id = a.id AND c.dest_res_name = 'RMB Yuan'

AND a.created_t >= v_date AND a.created_t < v_date + 1/24

GROUP BY a.icp_account_id,b.id);

insert into log_date values(sysdate,v_count);

COMMIT;

v_date := v_date + 1/24;  -- 下一个时段的起始时间

END LOOP;

END;

/

上下两段代码，唯一的区别就是

a.created_t >= TO_DATE('20030716','YYYYMMDD') AND a.created_t < TO_DATE('20030716','YYYYMMDD') + 1/24

和

a.created_t >= v_date AND a.created_t < v_date + 1/24

但上面能使用索引，而下面的无法使用

v_date := to_date(v_eff_date,'yyyymmdd');

v_eff_date 是存储过程的输入参数

为什么 在存储过程中，变量替换无法使用索引？

谢谢！！