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Oracle 查找與刪除表中重復(fù)記錄的步驟方法

 更新時(shí)間:2013年04月15日 22:02:57   作者:  
案例:一個(gè)應(yīng)用表中的一個(gè)字段是主鍵,向表中插入數(shù)據(jù)時(shí),先把數(shù)據(jù)放在臨時(shí)表中(沒(méi)有主鍵)然后再插入應(yīng)用表。

這時(shí)候如果臨時(shí)表中有重復(fù)數(shù)據(jù),無(wú)論是主鍵字段businessid有重復(fù),還是一整行有重復(fù)都會(huì)報(bào)出違反唯一主鍵約束錯(cuò)誤。

方法:group by XX having count(*)>1,rowid,distinct,temporary table,procedure

1、查詢(xún)表中的重復(fù)數(shù)據(jù)
a.重復(fù)一個(gè)字段

b.重復(fù)多個(gè)字段

c.重復(fù)一整行

創(chuàng)建測(cè)試表:

復(fù)制代碼 代碼如下:

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');

---------------以下為重復(fù)數(shù)據(jù)----------------------------------------------
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');


對(duì)于a的情況,只有businessid重復(fù)

復(fù)制代碼 代碼如下:

select * from cfa where businessid in (select businessid from cfa group by businessid having count(businessid)>1);

如果是b的情況,businessid 和name同時(shí)存在重復(fù)

復(fù)制代碼 代碼如下:

select * from cfa where (businessid,customer) in (select businessid,customer from cfa group by businessid,customer having count(*)>1);

對(duì)于c的情況,重復(fù)一整行

參考b的方法:

復(fù)制代碼 代碼如下:

select * from cfa where (businessid,customer,branchcode,data_date) in (select * from cfa group by businessid,customer,branchcode,data_date having count(*)>1);

2、刪除表中的重復(fù)數(shù)據(jù)
a情況,刪除表中多余的重復(fù)記錄,重復(fù)記錄是根據(jù)單個(gè)字段(businessid)來(lái)判斷,只留有rowid最小的記錄

也可以只保留rowid不是最小記錄,需要把代碼中的min改為max這里不再贅述。

復(fù)制代碼 代碼如下:

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,使用下面更簡(jiǎn)單高效的語(yǔ)句

復(fù)制代碼 代碼如下:

DELETE FROM cfa t
WHERE t.ROWID >
(SELECT MIN(X.ROWID) FROM cfa X WHERE X.businessid = t.businessid);

b情況,刪除表中多余的重復(fù)記錄(多個(gè)字段),只留有rowid最小的記錄

復(fù)制代碼 代碼如下:

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,使用下面更簡(jiǎn)單高效的語(yǔ)句

復(fù)制代碼 代碼如下:

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情況,這種情況就比較簡(jiǎn)單,使用臨時(shí)表方法

復(fù)制代碼 代碼如下:

create table cfabak as select distinct * from cfa;

truncate table cfa;--如果是生產(chǎn)最好對(duì)該表backup

Insert into cfa select * from cfabak;

commit;

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