删除反复行SQL举例
删除反复行SQL实验简单举例
说明：实验按顺序进行。前后存在关联性。阅读时请注意。打开文件夹更便于查看。
构造实验环境：
SQL> select count(*) from emp;
COUNT(*)
----------
14
SQL> alter table EMP drop constraint PK_EMP CASCADE;
--删除主键约束
SQL> insert into EMP select * from EMP;
--向EMP表中插入反复行
SQL> commit;
SQL> select count(*) from emp;
COUNT(*)
----------
28
以下举例单字段删除反复行
例1：查询出反复记录（单字段）
SQL> select * from emp
where empno in (select empno from emp group by empno having count
(empno) > 1);
--查找出emp表中多余的反复记录，反复记录是依据empno来判读
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7839 KING PRESIDENT 17-NOV-81 5000 10
7839 KING PRESIDENT 17-NOV-81 5000 10
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7900 JAMES CLERK 7698 03-DEC-81 950 30
28 rows selected.
例2：删除表中多余的反复记录，仅仅留有rowid最小的记录
SQL> delete from emp
where empno in (select empno from emp group by empno having count
(empno) > 1)
and rowid not in (select min(rowid) from emp group by empno having count(empno
)>1);
--删除表中多余的反复记录。反复记录是依据单个字段empno来判读
--保留rowid最小的行记录信息
14 rows deleted.
SQL> select * from emp ; --反复的行已经删除
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
14 rows selected.
SQL> insert into emp select * from emp;
SQL> insert into emp values(8888,'HYL','DBA',7839,sysdate,2000,'',60);
1 row created.
SQL> commit;
Commit complete.
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
8888 HYL DBA 7839 06-JUL-14 2000 60
29 rows selected.
多字段下：
例3：查询表中反复的记录（多字段）
SQL> select * from emp a
where (a.empno,a.deptno) in (select empno,deptno from emp group by empno,deptno having
count(*) > 1);
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7900 JAMES CLERK 7698 03-DEC-81 950 30
7900 JAMES CLERK 7698 03-DEC-81 950 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7839 KING PRESIDENT 17-NOV-81 5000 10
7566 JONES MANAGER 7839 02-APR-81 2975 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
28 rows selected.
例4：删除表中反复记录（多个字段），仅仅保留rowid最小的记录
SQL> delete from emp a
where (a.empno,a.deptno) in (select empno,deptno from emp group by empno,deptno having
count(*) > 1)
and rowid not in (select min(rowid) from emp group by empno,deptno having count(*)>1);
14 rows deleted.
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
8888 HYL DBA 7839 06-JUL-14 2000 60
15 rows selected.
SQL> rollback
2 ;
Rollback complete.
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
8888 HYL DBA 7839 06-JUL-14 2000 60
29 rows selected.
例5：查询表中多余的反复记录（多字段）。不包括rowid最小的记录
SQL> select * from emp a
where (a.empno,a.deptno) in (select empno,deptno from emp group by empno,deptno having
count(*) > 1)
and rowid not in (select min(rowid) from emp group by empno,deptno having count(*)>1);
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7900 JAMES CLERK 7698 03-DEC-81 950 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7566 JONES MANAGER 7839 02-APR-81 2975 20
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
14 rows selected.
SQL> commit;
Commit complete.
SQL> select * from emp; --emp表实际数据
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7369 SMITH CLERK 7902 17-DEC-80 800 20
7566 JONES MANAGER 7839 02-APR-81 2975 20
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7839 KING PRESIDENT 17-NOV-81 5000 10
8888 HYL DBA 7839 06-JUL-14 2000 60
29 rows selected.
***********************************************声明************************************************
原创作品，出自 “深蓝的blog” 博客。欢迎转载。转载时请务必注明出处（http://blog.csdn.net/huangyanlong）。
表述有错误之处。请您留言。不胜感激。
提醒：点击文件夹。更有助于您的查看。
*****************************************************************************************************
删除反复行SQL举例的更多相关文章
- SQL Server删除重复行的6个方法
SQL Server删除重复行是我们最常见的操作之一,下面就为您介绍六种适合不同情况的SQL Server删除重复行的方法,供您参考. 1.如果有ID字段,就是具有唯一性的字段 delect ta ...
- SQL查找删除重复行
本文讲述如何查找数据库里重复的行.这是初学者十分普遍遇到的问题.方法也很简单.这个问题还可以有其他演变,例如,如何查找“两字段重复的行”(#mysql IRC 频道问到的问题) 如何查找重复行 第一步 ...
- 【sql server】"已更新或删除的行值要么不能使该行成为唯一行,要么改变了多个行" 解决方案
#事故现场: 1.在手动修改某表中数据是,出现如下错误提示: 已更新或删除的行值要么不能使该行成为唯一行,要么改变了多个行 2.表结构及数据: #解决方法: 1.原因分析:提示被删除的行不是唯一行, ...
- PreparedStatement執行sql語句
import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import org ...
- Oracle删除重复行
Oracle删除重复行 分类: ORACLE2010-12-12 17:10 423人阅读 评论(0) 收藏 举报 oracletabledeleteintegerinsert.net 查询及删除重复 ...
- SqlServer_删除重复行只保留一条记录
前提:相同的数据重复往数据库写入,导致存在仅主键Id不同的重复数据,现在需要去除重复数据,仅保留重复数据中Id最大的一条 思路: 1.找出存在重复数据的记录,并取重复数据中最大的Id值 2.删 ...
- Linux之sed:删除某行以及替换
sed是一个很好的文件处理工具,本身是一个管道命令,主要是以行为单位进行处理,可以将数据行进行替换.删除.新增.选取等特定工作,下面先了解一下sed的用法sed命令行格式为: sed ...
- REDHAT一总复习1 vim编辑器的使用 删除所有者列 删除指定行
将文件/home/student/vimfile.txt 复制到server 上的/home/student/longlisting.txt . 根据下列要求,使用vim编辑器更改 /home/stu ...
- jquery Datatables 行数据删除、行上升、行下降功能演示
Datatables 是一款jquery表格插件.它是一个高度灵活的工具,可以将任何HTML表格添加高级的交互功能. 官方网站:http://www.datatables.net Datatables ...
随机推荐
- 【22】Vue 之 Vue Devtools
vue安装: # 最新稳定版 $ npm install vue # 全局安装 vue-cli $ npm install --global vue-cli # 创建一个基于 webpack 模板的新 ...
- RazorExtensions Templated Razor Delegates
原文发布时间为:2011-04-27 -- 来源于本人的百度文章 [由搬家工具导入] Templated Razor Delegates David Fowler turned me on to a ...
- SQL优化 ASP.NET ADO.NET
原文发布时间为:2009-08-26 -- 来源于本人的百度文章 [由搬家工具导入] 总的考虑方向 1) 根据数据使用的方式来设计数据访问层 2) 缓存数据，避免不必要的操 ...
- XmlRootElement
作用是 java对象 <---> xml文件 之间的转换 JAXB Annotation @XmlRootElement // xml 文件的根元素 @XmlElement @Xm ...
- 《Linux命令行与shell脚本编程大全 第3版》Linux命令行---24
以下为阅读<Linux命令行与shell脚本编程大全 第3版>的读书笔记,为了方便记录,特地与书的内容保持同步,特意做成一节一次随笔,特记录如下:
- HashMap和TreeMap的常用排序方法
一.简单描述 Map是键值对的集合接口,它的实现类主要包括:HashMap,TreeMap,HashTable以及LinkedHashMap等. TreeMap:能够把它保存的记录根据键(key)排序 ...
- hdu 3440(差分约束好题)
House Man Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total S ...
- html5---音频视频基础一
//html5 音频和视频 :标签 a: audio,video b: source :视频容器 a:容器文件,类似于压缩了一组文件 -音频轨道 -视频轨道 -元数据:封面,标题,字幕等 -格式:.a ...
- List集合使用注意的问题
在做自动保存草稿的功能遇到集合数据的问题,先贴自动保存草稿的代码 /** * 每5 秒保存一次草稿 */private void startDraftTimerTask(){ if (draftTim ...
- (转)C++常用函数汇总
1.标准C++库字符串类std::string的用法 begin 得到指向字符串开头的Iterator end 得到指向字符串结尾的Iterator rbegin ...