zoukankan      html  css  js  c++  java
  • MySQL中group_concat函数

    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'])

    基本查询
    mysql> select * from aa;
    +------+------+
    | id| name |
    +------+------+
    |1 | 10|
    |1 | 20|
    |1 | 20|
    |2 | 20|
    |3 | 200  |
    |3 | 500  |
    +------+------+
    6 rows in set (0.00 sec)

    以id分组,把name字段的值打印在一行,逗号分隔(默认)
    mysql> 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)

    以id分组,把name字段的值打印在一行,分号分隔
    mysql> 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)

    以id分组,把去冗余的name字段的值打印在一行,
    逗号分隔
    mysql> 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)

    以id分组,把name字段的值打印在一行,逗号分隔,以name排倒序mysql> 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)

    mysql的group_concat对应oracle的wm_concat

  • 相关阅读:
    页面布局
    导航栏nav的小例子
    块级元素和行内元素
    line-height的理解
    百度地图折线/线段点击不生效
    window系统上生成iosapp并且上架APPstore流程
    上架APPstore
    iOS证书(.p12)、描述文件(.mobileprovision)申请和HBuider打包及注意事项
    在vmware上安装mac os的虚拟机
    hbuilder X 使用苹果手机(ios)进行真机调试
  • 原文地址:https://www.cnblogs.com/skyblue/p/1798829.html
Copyright © 2011-2022 走看看