如何在 MySQL 中将重复值合并为一个，并用连字符分隔相应的值?
mysqlmysqli database更新于 2023/11/6 3:42:00
要合并，请使用 GROUP_CONCAT() 函数将两行中的某些属性合并为一行。作为分隔符，请使用连字符。
首先我们创建一个表 −
mysql> create table DemoTable1386 -> ( -> Title varchar(255), -> Name varchar(60) -> ); Query OK, 0 rows affected (0.67 sec)
使用 insert 命令在表中插入一些记录 −
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 语句显示表中的所有记录 −
mysql> select * from DemoTable1386;
这将产生以下输出 −
+-----------------------+---------------+ | 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)
以下是合并重复值的查询 −
mysql> select Title,group_concat(Name separator '----') from DemoTable1386 -> group by Title;
这将产生以下输出 −
+-----------------------+-------------------------------------+ | 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)
