IT技术浅谈
联系我们
主页 > IT技术浅谈 > IT技术浅谈

Oracle查找并删除表中的重复记录

时间:2018-11-13  编辑:凯发K

Oracle查找并删除表中的重复记录   案例:一个应用表中的一个字段是主键,向表中插入数据时,先把数据放在临时表中(没有主键)然后再插入应用表。 这时候如果临时表中有重复数据,无论是主键字段businessid有重复,还是一整行有重复都会报出违反唯一主键约束错误。 方法:group by XX having count(*)>1,rowid,distinct,temporary table,procedure 1、查询表中的重复数据 a.重复一个字段 b.重复多个字段 c.重复一整行 创建测试表: create table cfa (businessid number,customer varchar2(50),branchcode varchar2(10),data_date varchar2(10)); insert into cfa values (1,'Albert','SCB','2011-11-11'); insert into cfa values (2,'Andy','DB','2011-11-12'); insert into cfa values (3,'Allen','HSBC','2011-11-13'); ---------------以下为重复数据---------------------------------------------- insert into cfa values (1,'Alex','ICBC','2011-11-14'); insert into cfa values (1,'Albert','CTBK','2011-11-15'); insert into cfa values (1,'Albert','SCB','2011-11-11'); 对于a的情况,只有businessid重复 select * from cfa where businessid in (select businessid from cfa group by businessid having count(businessid)>1); 如果是b的情况,businessid 和name同时存在重复 select * from cfa where (businessid,customer) in (select businessid,customer from cfa group by businessid,customer having count(*)>1); 对于c的情况,重复一整行 参考b的方法:select * from cfa where (businessid,customer,branchcode,data_date) in (select * from cfa group by businessid,customer,branchcode,data_date having count(*)>1); 2、删除表中的重复数据 a情况,删除表中多余的重复记录,重复记录是根据单个字段(businessid)来判断,只留有rowid最小的记录 也可以只保留rowid不是最小记录,需要把代码中的min改为max这里不再赘述。 delete from cfa where businessid in (select businessid from cfa group by businessid having count(businessid) > 1) and rowid not in (select min(rowid) from cfa group by businessid having count(businessid) > 1); 或者,使用下面更简单高效的语句 DELETE FROM cfa t WHERE t.ROWID > (SELECT MIN(X.ROWID) FROM cfa X WHERE X.businessid = t.businessid); b情况,删除表中多余的重复记录(多个字段),只留有rowid最小的记录 delete from cfa where (businessid,customer) in (select businessid,customer from cfa group by businessid,customer having count(*) > 1) and rowid not in (select min(rowid) from cfa group by businessid,customer having count(*) > 1); 或者,使用下面更简单高效的语句 DELETE FROM cfa t WHERE t.ROWID > (SELECT MIN(X.ROWID) FROM cfa X WHERE X.businessid = t.businessid and x.customer = t.customer); c情况,这种情况就比较简单,使用临时表方法 create table cfabak as select distinct * from cfa; truncate table cfa;--如果是生产最好对该表backup Insert into cfa select * from cfabak; commit;

http://www.bkjia.com/oracle/481951.htmlwww.bkjia.comtruehttp://www.bkjia.com/oracle/481951.htmlTechArticleOracle查找并删除表中的重复记录 案例:一个应用表中的一个字段是主键,向表中插入数据时,先把数据放在临时表中(没有主键)然后再插...

本文源自: AG游戏网站

Copyright © 2005-2016 http://www.firebugkc.com AG游戏网站_亚洲最佳百家乐游戏平台_AG环亚集团_网易体育版权所有 AG游戏网站_亚洲最佳百家乐游戏平台_AG环亚集团_网易体育