数据库
首页 > 数据库> > Oracle数据库sql语句处理业务表重复数据取其一

Oracle数据库sql语句处理业务表重复数据取其一

作者:互联网

背景:

在日常的工作中,我们会遇见一张表中存在重复的数据,这个重复的数据是指几个字段组成一个唯一索引的,但是因为在加工数据的过程中,会去掉这个唯一索引,但是在迁移到业务表中需要这个唯一索引,或者是业务要求等条件的,如下就演示了如何取其一:

如下就是业务,我们需要根据业务的需求取出重复数据中的其中一条数据 

-- Create table
create table sc_class
(
  id         VARCHAR2(32) not null,
  class_id   VARCHAR2(20) not null,
  xm         VARCHAR2(50) not null,
  sfzjhm     VARCHAR2(30) not null,
  sfzjlx     VARCHAR2(5)  not null,
  kc         VARCHAR2(5),
  cj         VARCHAR2(5),
  class_pm   VARCHAR2(6),
  lrrq      DATE,
  lrr_dm    CHAR(11),
  yxbz      CHAR(1) not null,
)
tablespace TS_CLASS_DATA
  pctfree 10
  initrans 1
  maxtrans 255
  storage
  (
    initial 64K
    next 1M
    minextents 1
    maxextents unlimited
  );
-- Add comments to the table 
comment on table sc_class
  is '学生信息';
-- Add comments to the columns 
comment on column sc_class.id
  is 'ID';
comment on column sc_class.class_id
  is '班级ID';
comment on column sc_class.xm
  is '姓名';
comment on column sc_class.sfzjhm
  is '身份证件号码';
comment on column sc_class.sfzjlx
  is '身份证件类型';
comment on column sc_class.kc
  is '课程';
comment on column sc_class.cj
  is '成绩';
comment on column sc_class.class_pm
  is '年级排名';
comment on column sc_class.lrrq
  is '修改日期';
comment on column sc_class.lrr_dm
  is '修改人代码';
comment on column sc_class.yxbz
  is '有效标志 Y:是 N:否';
-- Create/Recreate primary, unique and foreign key constraints 
alter table sc_class
  add constraint PK_CLASSID primary key (ID)
  using index 
  tablespace TS_CLASS_IDX
  pctfree 10
  initrans 2
  maxtrans 255
  storage
  (
    initial 64K
    next 1M
    minextents 1
    maxextents unlimited
  );

 sql语句如下:

这里就是取出来的rowid中最大那个值的数据,

select *
  from sc_class t
 where id in
       (select a.id
          from sc_class a
         where rowid in
               (select max(rowid)
                  from sc_class b
                 where b.yxbz = 'Y'
                   and (b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc) in
                       (select d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                          from sc_class d
                         where where d.yxbz = 'Y'
                         group by d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                        having count(1) > 1)
                 group by b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc));

核心的sql语句如下: 

--方法一
select * from tb_supply where rowid=any(select max(rowid) from tb_supply group by phone_id)
--方法二
select * from tb_supply where rowid in (select max(rowid) from tb_supply group by phone_id)  

 总结:这里就是将重复的数据按照一定的规则取出rowid最大的那个值,这里只是查询的,如果还需要将查询的数据删除或者是更新,可以按照如下的:

-----更新的SQL:
update sc_class t
   set t.yxbz = 'N'
 where id in
       (select a.id
          from sc_class a
         where rowid in
               (select max(rowid)
                  from sc_class b
                 where b.yxbz = 'Y'
                   and (b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc) in
                       (select d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                          from sc_class d
                         where where d.yxbz = 'Y'
                         group by d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                        having count(1) > 1)
                 group by b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc));

-----删除的sql:
delete sc_class t 
 where t.id in
       (select a.id
          from sc_class a
         where rowid in
               (select max(rowid)
                  from sc_class b
                 where b.yxbz = 'Y'
                   and (b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc) in
                       (select d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                          from sc_class d
                         where where d.yxbz = 'Y'
                         group by d.class_id, d.xm, d.sfzjhm, d.sfzjlx, d.kc
                        having count(1) > 1)
                 group by b.class_id, b.xm, b.sfzjhm, b.sfzjlx, b.kc));

 到此重复数据取其一,或者是更新/删除其一的,同学们可以根据需求进行修改。

标签:语句,xm,class,sc,sfzjhm,sql,Oracle,where,id
来源: https://blog.csdn.net/jiang0615csdn/article/details/121884646