从MySQL提取数据以便使用重复值进行格式化的最有效方法是什么
为此，您可以使用GROUP_CONCAT()。让我们首先创建一个表-
mysql> create table DemoTable1561 -> ( -> StudentName varchar(20), -> Title text -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1561 values('Adam','Learning Java');
mysql> insert into DemoTable1561 values('Bob','Learning C');
mysql> insert into DemoTable1561 values('Adam','Learning Spring and Hibernate Framework');
mysql> insert into DemoTable1561 values('Carol','Learning MySQL from basic');使用select语句显示表中的所有记录-
mysql> select * from DemoTable1561;
这将产生以下输出-
+-------------+-----------------------------------------+ | StudentName | Title | +-------------+-----------------------------------------+ | Adam | Learning Java | | Bob | Learning C | | Adam | Learning Spring and Hibernare Framework | | Carol | Learning MySQL from basic | +-------------+-----------------------------------------+ 4 rows in set (0.00 sec)
这是从MySQL中提取数据以便格式化的查询-
mysql> select StudentName,group_concat(Title separator ',') as FormattedOutput from DemoTable1561 -> group by StudentName;
这将产生以下输出-
+-------------+-------------------------------------------------------+ | StudentName | FormattedOutput | +-------------+-------------------------------------------------------+ | Adam | Learning Java,Learning Spring and Hibernate Framework | | Bob | Learning C | | Carol | Learning MySQL from basic | +-------------+-------------------------------------------------------+ 3 rows in set (0.00 sec)