MySQL GROUP BY 和 CONCAT() 显示不同的姓和名
mysqlmysqli database更新于 2025/12/12 0:12:17
首先我们创建一个表 −
mysql> create table DemoTable ( FirstName varchar(100), LastName varchar(100) ); Query OK, 0 rows affected (0.92 sec) mysql> alter table DemoTable add index(FirstName,LastName); Query OK, 0 rows affected (1.00 sec) Records: 0 Duplicates: 0 Warnings: 0
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable values('Adam','Smith');
Query OK, 1 row affected (0.73 sec)
mysql> insert into DemoTable values('Adam','Smith');
Query OK, 1 row affected (1.17 sec)
mysql> insert into DemoTable values('John','Doe');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values('Carol','Taylor');
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable values('John','Doe');
Query OK, 1 row affected (0.66 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
这将产生以下输出 −
+-----------+----------+ | FirstName | LastName | +-----------+----------+ | Adam | Smith | | Adam | Smith | | Carol | Taylor | | John | Doe | | John | Doe | +-----------+----------+ 5 rows in set (0.00 sec)
以下是组合不同名字和姓氏的查询 −
mysql> select concat(FirstName,' ',LastName) as combinedName from DemoTable group by LastName,FirstName;
这将产生以下输出 −
+--------------+ | combinedName | +--------------+ | Adam Smith | | Carol Taylor | | John Doe | +--------------+ 3 rows in set (0.00 sec)
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mysql 参考教程 - 该教程包含有关 mysql 的更多信息:https://www.cainiaomax.com/mysql/
