SQL函数Group_concat的用法及说明

group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符'])

SELECT * FROM testgroup

SELECT id,GROUP_CONCAT(score) FROM testgroup GROUP BY id

SELECT id,GROUP_CONCAT(DISTINCT score) FROM testgroup GROUP BY id

SELECT id,GROUP_CONCAT(score ORDER BY score DESC) FROM testgroup GROUP BY id

SELECT id,GROUP_CONCAT(score SEPARATOR ';') FROM testgroup GROUP BY id

use Mysql;
SHOW VARIABLES LIKE "group_concat_max_len"; #查询最大值

SET GLOBAL group_concat_max_len=10240000;
SET SESSioN group_concat_max_len=10240000;