如何在MySQL中将重复的值合并为一个，并用连字符将其对应的值组合起来？
要进行合并，请使用GROUP_CONCAT()函数将两行中的某些属性合并为一。作为连字符，请使用连字符。
让我们首先创建一个表-
mysql> create table DemoTable1386 -> ( -> Title varchar(255), -> Name varchar(60) -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1386 values('Introduction to MySQL','Paul DuBois');
mysql> insert into DemoTable1386 values('Java in Depth','Khalid Mughal');
mysql> insert into DemoTable1386 values('Introduction to MySQL','Russell Dyer');
mysql> insert into DemoTable1386 values('Java in Depth','Joshua Bloch');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)