MySQL 如何将重复值组合成一个，对应值以连字符分隔

要组合，使用GROUP_CONCAT() 函数将两个行中的某些属性组合成一个。以连字符为分隔符。

首先创建一个表−

mysql> create table DemoTable1386
    -> (
    -> Title varchar(255),
    -> Name varchar(60)
    -> );
Query OK, 0 rows affected (0.67 sec)

使用 insert 命令将一些记录插入表中−

mysql> insert into DemoTable1386 values('Introduction to MySQL','Paul DuBois');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1386 values('Java in Depth','Khalid Mughal');
Query OK, 1 row affected (0.48 sec)
mysql> insert into DemoTable1386 values('Introduction to MySQL','Russell Dyer');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable1386 values('Java in Depth','Joshua Bloch');
Query OK, 1 row affected (0.17 sec)

使用 select 语句从表中显示所有记录−

mysql> select * from DemoTable1386;

将会产生以下输出−

+-----------------------+---------------+
| Title                 | Name          |
+-----------------------+---------------+
| Introduction to MySQL | Paul DuBois   |
| Java in Depth         | Khalid Mughal |
| Introduction to MySQL | Russell Dyer  |
| Java in Depth         | Joshua Bloch  |
+-----------------------+---------------+
4 rows in set (0.00 sec)

以下是用于组合重复值的查询−

mysql> select Title,group_concat(Name separator '----') from DemoTable1386
-> group by Title;

将产生以下输出−

+-----------------------+-------------------------------------+
| Title                 | group_concat(Name separator '----') |
+-----------------------+-------------------------------------+
| Introduction to MySQL | Paul DuBois----Russell Dyer         |
| Java in Depth         | Khalid Mughal----Joshua Bloch       |
+-----------------------+-------------------------------------+
2 rows in set (0.00 sec)

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