如何将 MySQL 不同的查询结果连接成字符串?
mysqlmysqli database更新于 2025/5/21 18:52:17
使用 MySQL 中的 group_concat() 函数进行连接。让我们首先创建一个表 −
mysql> create table DemoTable -> ( -> Subject varchar(10) -> ); Query OK, 0 rows affected (0.43 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable values('C');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable values('C++');
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable values('C++');
Query OK, 1 row affected (0.06 sec)
mysql> insert into DemoTable values('MongoDB');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable values('MySQL');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('MongoDB');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('MongoDB');
Query OK, 1 row affected (0.34 sec)
mysql> insert into DemoTable values('Java');
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable values('Java');
Query OK, 1 row affected (0.10 sec)
Display all records from the table using select statement:
mysql> select *from DemoTable;
输出
这将产生以下输出 −
+---------+ | Subject | +---------+ | C | | C++ | | C++ | | MongoDB | | MySQL | | MongoDB | | MongoDB | | Java | | Java | +---------+ 9 rows in set (0.00 sec)
以下是将 SQL 不同的查询结果连接成一个字符串的查询 −
mysql> select group_concat(tbl.sub) from (select Subject sub from DemoTable group by Subject ) tbl;
输出
这将产生以下输出 −
+--------------------------+ | group_concat(tbl.sub) | +--------------------------+ | C,C++,MongoDB,MySQL,Java | +--------------------------+ 1 row in set (0.04 sec)
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