GROUP BY另一个MySQL表中的一列
为此，可以使用CREATETABLEASSELECT语句。让我们首先创建一个表-
mysql> create table DemoTable1 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CountryName varchar(20) -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1(CountryName) values('US');
mysql> insert into DemoTable1(CountryName) values('UK');
mysql> insert into DemoTable1(CountryName) values('AUS');
mysql> insert into DemoTable1(CountryName) values('UK');
mysql> insert into DemoTable1(CountryName) values('UK');
mysql> insert into DemoTable1(CountryName) values('US');
mysql> insert into DemoTable1(CountryName) values('AUS');使用select语句显示表中的所有记录-
mysql> select *from DemoTable1;
输出结果
+----+-------------+ | Id | CountryName | +----+-------------+ | 1 | US | | 2 | UK | | 3 | AUS | | 4 | UK | | 5 | UK | | 6 | US | | 7 | AUS | +----+-------------+ 7 rows in set (0.00 sec)
以下是对另一个表中的GROUPBY列的查询-
mysql> create table DemoTable2 AS select *from DemoTable group by CountryName; Records: 3 Duplicates: 0 Warnings: 0
现在检查新表中的记录-
mysql> select *from DemoTable2;
输出结果
+----+-------------+ | Id | CountryName | +----+-------------+ | 1 | US | | 2 | UK | | 3 | AUS | +----+-------------+ 3 rows in set (0.00 sec)