Mariadb MySQL、Mariadb中GROUP_CONCAT函数使用介绍

MySQL、Mariadb中GROUP_CONCAT 函数使用介绍

By:授客 QQ：1033553122

语法：

GROUP_CONCAT([DISTINCT] column_name [ORDER BY 序字段 ASC/DESC] [SEPARATOR '分隔符'])

注：测试时发现，排序似乎不起作用

实践

构造数据：

CREATE TABLE tb_test(

order_id INT,

goods_id INT,

user_name VARCHAR(7)

);

INSERT INTO tb_test VALUES(1000000001, 1, '授客'), (1000000001, 2, '授客'), (1000000001, 3, '授客'),(1000000002, 4, '小谢'), (1000000002, 5, '小谢'), (1000000002, 6, '小谢');

SELECT * FROM tb_test;

例子1：

查询每个用户购买的商品(按user_name分组，显示其购买的所有商品)

SELECT t1.`order_id` AS '订单号',

t1.`user_name` AS '用户名',

GROUP_CONCAT((CASE WHEN t1.`goods_id` = 1 THEN '小苹果' 
WHEN t1.`goods_id` = 2 THEN '雪梨'
WHEN t1.`goods_id` = 3 THEN '香蕉'
WHEN t1.`goods_id` = 4 THEN '小李子'
WHEN t1.`goods_id` = 5 THEN '芭乐'
WHEN t1.`goods_id` = 6 THEN '葡萄'
END)) AS '商品'

FROM tb_test t1

GROUP BY t1.`user_name`;

结果：

例子2：

查询每个用户购买的商品(按user_name分组，显示其购买的所有商品)，商品之间用";"分隔

SELECT t1.`order_id` AS '订单号',

t1.`user_name` AS '用户名',

GROUP_CONCAT((CASE WHEN t1.`goods_id` = 1 THEN '小苹果' 
WHEN t1.`goods_id` = 2 THEN '雪梨'
WHEN t1.`goods_id` = 3 THEN '香蕉'
WHEN t1.`goods_id` = 4 THEN '小李子'
WHEN t1.`goods_id` = 5 THEN '芭乐'
WHEN t1.`goods_id` = 6 THEN '葡萄'
END) SEPARATOR ';') AS '商品'

FROM tb_test t1

GROUP BY t1.`user_name`;

结果：

例子3：

查询每个用户购买的商品(按user_name分组，显示其购买的所有商品)，商品名称不重复

SELECT t1.`order_id` AS '订单号',

t1.`user_name` AS '用户名',

GROUP_CONCAT((CASE WHEN t1.`goods_id` = 1 THEN '小苹果' 
WHEN t1.`goods_id` = 2 THEN '雪梨'

WHEN t1.`goods_id` = 3 THEN '香蕉'
WHEN t1.`goods_id` = 4 THEN '小李子'

WHEN t1.`goods_id` = 5 THEN '芭乐'
WHEN t1.`goods_id` = 6 THEN '葡萄'
END) ) AS '商品'

FROM tb_test t1

GROUP BY t1.`user_name`;

运行结果：

修改脚本如下：

SELECT t1.`order_id` AS '订单号',

t1.`user_name` AS '用户名',

GROUP_CONCAT(DISTINCT (CASE WHEN t1.`goods_id` = 1 THEN
'小苹果' 
WHEN t1.`goods_id` = 2 THEN '雪梨'

WHEN t1.`goods_id` = 3 THEN '香蕉'
WHEN t1.`goods_id` = 4 THEN '小李子'

WHEN t1.`goods_id` = 5 THEN '芭乐'
WHEN t1.`goods_id` = 6 THEN '葡萄'
END) ) AS '商品'

FROM tb_test t1

GROUP BY t1.`user_name`;

运行结果如下：