如果只执行 select W.A, W.B, W.C, W.D from WXXJ W left JOIN WTTX X ON W.A = X.D left JOIN WJJD D ON D.CD = X.Q where 1 = 1 AND D.shen_id = '520000' order by SY desc 会很快但加了分页后 select * from( select W.A, W.B, W.C, W.D from WXXJ W left JOIN WTTX X ON W.A = X.D left JOIN WJJD D ON D.CD = X.Q where 1 = 1 AND D.shen_id = '520000' order by SY desc ) where rownum <=20 就很慢了
1.根据ROWID来分 select * from t_xiaoxi where rowid in(select rid from (select rownum rn,rid from(select rowid rid,cid fromt_xiaoxi order by cid desc) where rownum<10000) where rn>9980) order by cid desc; 执行时间0.03秒 2.按分析函数来分 select * from (select t.*,row_number() over(order by cid desc) rk from t_xiaoxi t) where rk<10000 and rk>9980; 执行时间1.01秒 3.按ROWNUM来分 select * from(select t.*,rownum rn from(select * from t_xiaoxi order by cid desc) t where rownum<10000) wherern>9980;执行时间0.1秒 其中t_xiaoxi为表名称,cid为表的关键字段,取按CID降序排序后的第9981-9999条记录,t_xiaoxi表有70000多条记录 1的效率最好,3次之,2最差
select W.A, W.B, W.C, W.D from WXXJ W
left JOIN WTTX X ON W.A = X.D
left JOIN WJJD D ON D.CD = X.Q
where 1 = 1 AND D.shen_id = '520000' order by SY desc
会很快但加了分页后
select * from( select W.A, W.B, W.C, W.D from WXXJ W
left JOIN WTTX X ON W.A = X.D
left JOIN WJJD D ON D.CD = X.Q
where 1 = 1 AND D.shen_id = '520000' order by SY desc ) where rownum <=20
就很慢了
select * from t_xiaoxi where rowid in(select rid from (select rownum rn,rid from(select rowid rid,cid fromt_xiaoxi order by cid desc) where rownum<10000) where rn>9980) order by cid desc;
执行时间0.03秒
2.按分析函数来分
select * from (select t.*,row_number() over(order by cid desc) rk from t_xiaoxi t) where rk<10000 and rk>9980;
执行时间1.01秒
3.按ROWNUM来分
select * from(select t.*,rownum rn from(select * from t_xiaoxi order by cid desc) t where rownum<10000) wherern>9980;执行时间0.1秒
其中t_xiaoxi为表名称,cid为表的关键字段,取按CID降序排序后的第9981-9999条记录,t_xiaoxi表有70000多条记录
1的效率最好,3次之,2最差