Lag和Lead分析函数可以在同一次查询中取出同一字段的前N行的数据(Lag)和后N行的数据(Lead)作为独立的列。
以下是Lead的范例：
找出上下两条记录中，borrow_nid,user_id,account,addip相同、且addtime之差少于5秒的记录
for r1 in (
select id,borrow_nid,user_id,account,addip,addtime from 表名1 a4
where exists (
select 1 from (
select a2.id,a2.borrow_nid,a2.user_id,a2.account,a2.addip,a2.addtime,id2,(a2.addtime2-a2.addtime) as addtime2 from (
select a1.id,a1.borrow_nid,a1.user_id,a1.account,a1.addip,a1.addtime,
lead(a1.id,1,0) over(order by rownum) as id2,
lead(a1.borrow_nid,1,0) over(order by rownum) as borrow_nid2,
lead(a1.user_id,1,0) over(order by rownum) as user_id2,
lead(a1.account,1,0) over(order by rownum) as account2,
lead(a1.addip,1,0) over(order by rownum) as addip2,
lead(a1.addtime,1,0) over(order by rownum) as addtime2
from (
-- data start
select t1.id,t1.borrow_nid,t1.user_id,t1.account,t1.addip,t1.addtime
from 表名1 t1
where exists (
select 1 from (
select borrow_nid,user_id,account,addip,count(id) as count from 表名1
where addtime>=stime and addtime<etime
group by borrow_nid,user_id,account,addip
having count(id)>1
) t2 where t2.borrow_nid=t1.borrow_nid and t2.user_id=t1.user_id and t2.account=t1.account
) and addtime>=stime and addtime<etime
order by t1.borrow_nid,t1.user_id,t1.account,t1.addip,t1.addtime
-- data end
) a1
) a2 where borrow_nid=borrow_nid2 and user_id=user_id2 and account=account2 and addip=addip2 and (addtime2-addtime)<5000
) a3 where a4.id=a3.id or a4.id=a3.id2
) order by a4.borrow_nid,a4.user_id,a4.account,a4.addip,a4.addtime
) loop
v_data_id := r1.id;
v_borrow_nid := r1.borrow_nid;
v_user_id := r1.user_id;
v_account := r1.account;
v_addip := r1.addip;
v_addtime := r1.addtime;
insert into 表名2(id,data_type,data_id,borrow_nid,user_id,account,addip,addtime)
values (seq_repeat_datas_alarm.nextval, 'tender', v_data_id, v_borrow_nid, v_user_id, v_account, v_addip, v_addtime);
end loop;