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求100以内的质数
WITH T AS (SELECT ROWNUM RN FROM DUAL CONNECT BY LEVEL SELECT RN FROM T WHERE RN > 1 MINUS SELECT A.RN * B.RN FROM T A, T B WHERE A.RN 1 AND B.RN > 1;转载 2015-03-23 16:27:52 · 452 阅读 · 0 评论 -
oracle 100以内质数
WITHTAS(SELECTROWNUMRNFROMDUALCONNECTBYLEVELselect*fromtwherernnotin(SELECTdistincta.RNFROMTa,tbWHEREmod(a.rn,b.rn)=0anda.rn>1andb.rn>1anda.rn>b.rn原创 2015-03-23 17:07:38 · 751 阅读 · 0 评论 -
行转列小练习
原始数据：select * from date_tab;目标格式：解法一：select year, Sum(case when month =1 then amount end) as m1, Sum(Case when month=2 then amount end) as m2, Sum(Case when month=3 then原创 2015-03-24 13:33:15 · 462 阅读 · 0 评论 -
点到点距离
--建表语句和数据CREATE TABLE DISTANCE_TT( ODF1 NUMBER, ODF2 NUMBER, DISTANCE NUMBER);INSERT INTO DISTANCE_TT(ODF1, ODF2, DISTANCE) VALUES (9,10,4);INSERT INTO DISTANCE_TT(ODF1, ODF2, DIS原创 2015-04-17 17:06:14 · 654 阅读 · 0 评论 -
exists ，not exists改写成in 和 not in 时，要注意null值的情况，会影响结果
---not existsselect count(distinct a.pos_mer_id)from tests awhere a.stat_flag='C' and not exists(select 1 fromhfods.tests bwhere b.stat_flag='N' and b.pos_mer_id=a.pos_mer_id);改写成no原创 2015-08-30 12:54:05 · 1344 阅读 · 3 评论