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在MySQL中查找重复行（复合键）？

2024-04-28 19:14:04 497

要查找重复的行，请在MySQL中使用GROUPBY和HAVING。让我们首先创建一个表-

mysql> create table DemoTable1494
   -> (
   -> ShippingDate datetime,
   -> CustomerCountryName varchar(20)
   -> );

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable1494 values('2018-09-10 12:34:50','US');
mysql> insert into DemoTable1494 values('2019-09-10 12:34:50','AUS');
mysql> insert into DemoTable1494 values('2018-09-10 11:00:00','US');
mysql> insert into DemoTable1494 values('2017-12-31 01:10:40','UK');
mysql> insert into DemoTable1494 values('2019-09-10 05:00:50','AUS');

使用select语句显示表中的所有记录-

mysql> select * from DemoTable1494;

这将产生以下输出-

+---------------------+---------------------+
| ShippingDate        | CustomerCountryName |
+---------------------+---------------------+
| 2018-09-10 12:34:50 | US                  |
| 2019-09-10 12:34:50 | AUS                 |
| 2018-09-10 11:00:00 | US                  |
| 2017-12-31 01:10:40 | UK                  |
| 2019-09-10 05:00:50 | AUS                 |
+---------------------+---------------------+
5 rows in set (0.00 sec)

以下是在MySQL中查找重复行的查询-

mysql> select ShippingDate,CustomerCountryName,count(*) as c
   -> from DemoTable1494
   -> group by date(ShippingDate),CustomerCountryName
   -> having c >=2
   -> order by c;

这将产生以下输出-

+---------------------+---------------------+---+
| ShippingDate        | CustomerCountryName | c |
+---------------------+---------------------+---+
| 2018-09-10 12:34:50 | US                  | 2 |
| 2019-09-10 12:34:50 | AUS                 | 2 |
+---------------------+---------------------+---+
2 rows in set (0.00 sec)

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在MySQL中查找重复行（复合键）？

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