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标题: Oracle 查找与删除表中重复记录的步骤方法 [打印本页]
作者: 万望 时间: 2020-6-16 22:39
标题: Oracle 查找与删除表中重复记录的步骤方法
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');
复制代码对于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);
复制代码如果是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);
复制代码对于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);
复制代码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);
复制代码或者,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);
复制代码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);
复制代码或者,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);
复制代码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;
复制代码
作者: 万望 时间: 2020-6-16 22:40
步骤全给你们贴出咋样
作者: 陈晓龙 时间: 2020-6-17 21:05
有描述,有案例。不错
作者: 陈晓龙 时间: 2020-6-17 21:05
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