group_concat函数将id相同的行数据合并起来
group_concat这个函数能将相同的行组合起来,省老事了。
MySQL中group_concat函数
完整的语法如下:
group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符']) 复制代码
1.基本查询
Sql代码
select * from aa; +------+------+ | id| name | +------+------+ |1 | 10| |1 | 20| |1 | 20| |2 | 20| |3 | 200 | |3 | 500 | +------+------+ 6 rows in set (0.00 sec) 复制代码
2. 以id分组,把name字段的值打印在一行,逗号分隔(默认)
Sql代码
select id,group_concat(name) from aa group by id; +------+--------------------+ | id| group_concat(name) | +------+--------------------+ |1 | 10,20,20| |2 | 20 | |3 | 200,500| +------+--------------------+ 3 rows in set (0.00 sec) 复制代码
3. 以id分组,把name字段的值打印在一行,分号分隔
sql代码
select id,group_concat(name separator ';') from aa group by id; +------+----------------------------------+ | id| group_concat(name separator ';') | +------+----------------------------------+ |1 | 10;20;20 | |2 | 20| |3 | 200;500 | +------+----------------------------------+ 3 rows in set (0.00 sec) 复制代码
4. 以id分组,把去冗余的name字段的值打印在一行,并用逗号分隔
Sql代码
select id,group_concat(distinct name) from aa group by id; +------+-----------------------------+ | id| group_concat(distinct name) | +------+-----------------------------+ |1 | 10,20| |2 | 20 | |3 | 200,500 | +------+-----------------------------+ 3 rows in set (0.00 sec) 复制代码
5.以id分组,把name字段的值打印在一行,逗号分隔,以name排倒序
Sql代码
select id,group_concat(name order by name desc) from aa group by id; +------+---------------------------------------+ | id| group_concat(name order by name desc) | +------+---------------------------------------+ |1 | 20,20,10 | |2 | 20| |3 | 500,200| +------+---------------------------------------+ 3 rows in set (0.00 sec)
作者:ratelfu
链接:https://juejin.cn/post/7022227357993795620