使用 MySQL 将多行和多列连接成一行
mysqlmysqli database更新于 2024/2/11 22:03:00
要将多行和多列连接成一行，可以使用 GROUP_CONCAT() 和 CONCAT()。让我们首先创建一个表 −
mysql> create table DemoTable1463 -> ( -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ClientName varchar(20), -> ClientAge int -> ); Query OK, 0 rows affected (1.37 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable1463(ClientName,ClientAge) values('Adam Smith',34);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable1463(ClientName,ClientAge) values('John Doe',29);
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable1463(ClientName,ClientAge) values('David Miller',NULL);
Query OK, 1 row affected (0.28 sec)
mysql> insert into DemoTable1463(ClientName,ClientAge) values('John Smith',32);
Query OK, 1 row affected (0.14 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable1463;
这将产生以下输出 −
+----------+--------------+-----------+ | ClientId | ClientName | ClientAge | +----------+--------------+-----------+ | 1 | Adam Smith | 34 | | 2 | John Doe | 29 | | 3 | David Miller | NULL | | 4 | John Smith | 32 | +----------+--------------+-----------+ 4 rows in set (0.00 sec)
以下是将多行和多列连接成一行的查询 −
mysql> select group_concat(concat(ClientId,':',ClientName,':',IFNULL(ClientAge,''))) from DemoTable1463;
这将产生以下输出 −
+------------------------------------------------------------------------+ | group_concat(concat(ClientId,':',ClientName,':',IFNULL(ClientAge,''))) | +------------------------------------------------------------------------+ | 1:Adam Smith:34,2:John Doe:29,3:David Miller:,4:John Smith:32 | +------------------------------------------------------------------------+ 1 row in set (0.04 sec)
