删除重复数据只保存一条--ms sql及oracle实现方法_mssql 只保留一条数据-优快云博客

本文链接：https://blog.youkuaiyun.com/wang7dao/article/details/7718380

本文介绍如何使用SQL在MSSQL和Oracle数据库中批量删除重复记录的方法。通过创建临时表并插入示例数据，然后利用子查询和聚合函数确定哪些重复记录保留，最终实现去除重复项的功能。

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ms sql方法：

declare @sss table (ID int, Name varchar(10), address varchar(10))
insert into @sss select 1,'小王','重庆'
insert into @sss select 2,'小张','北京'
insert into @sss select 3,'小明','上海'
insert into @sss select 4,'小红','重庆'
insert into @sss select 5,'小李','重庆'
insert into @sss select 6,'小白','北京'
insert into @sss select 7,'小红','上海'
insert into @sss select 8,'小红','重庆'

delete from @sss where id not in(select min(id) from @sss group by name,address)

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oracle方法：

SQL> CREATE TABLE test_delete(
2 name varchar(10),
3 value INT
4 );
表已创建。

SQL> INSERT INTO test_delete
2 SELECT '张三', 100 FROM dual
3 UNION ALL SELECT '张三', 100 FROM dual
4 UNION ALL SELECT '李四', 80 FROM dual
5 UNION ALL SELECT '王五', 80 FROM dual
6 UNION ALL SELECT '王五', 80 FROM dual
7 UNION ALL SELECT '赵六', 90 FROM dual
8 UNION ALL SELECT '赵六', 70 FROM dual;
已创建7行。

SQL> SELECT
2    ROWID,
3    name,
4    value
5 FROM
6    test_delete;
ROWID              NAME            VALUE
------------------ ---------- ----------
AAAM2mAAGAAAAOXAAA 张三              100
AAAM2mAAGAAAAOXAAB 张三              100
AAAM2mAAGAAAAOXAAC 李四               80
AAAM2mAAGAAAAOXAAD 王五               80
AAAM2mAAGAAAAOXAAE 王五               80
AAAM2mAAGAAAAOXAAF 赵六               90
AAAM2mAAGAAAAOXAAG 赵六               70
已选择7行。

SQL> DELETE test_delete
WHERE (name, value) IN (SELECT name, value FROM test_delete GROUP BY name, value HAVING COUNT(1) > 1)
AND rowid NOT IN (SELECT MIN(rowid) FROM test_delete GROUP BY name, value HAVING COUNT(1) > 1);

已删除2行。

SQL> SELECT
2    ROWID,
3    name,
4    value
5 FROM
6    test_delete;

ROWID              NAME            VALUE
------------------ ---------- ----------
AAAM2mAAGAAAAOXAAA 张三              100
AAAM2mAAGAAAAOXAAC 李四               80
AAAM2mAAGAAAAOXAAD 王五               80
AAAM2mAAGAAAAOXAAF 赵六               90
AAAM2mAAGAAAAOXAAG 赵六               70