表结构及数据

DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
`name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`course_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of course
-- ----------------------------
INSERT INTO `course` VALUES ('李明', '阅读赏析');
INSERT INTO `course` VALUES ('李明', '摄影');
INSERT INTO `course` VALUES ('李明', '太极剑');
INSERT INTO `course` VALUES ('司马光', '马克思主义基本原理');
INSERT INTO `course` VALUES ('司马光', '摄影');
INSERT INTO `course` VALUES ('叶问', '阅读赏析');
INSERT INTO `course` VALUES ('叶问', '法语');

SET FOREIGN_KEY_CHECKS = 1;

选修课程表

select t.name as '姓名',t.course_name as '课程' from course t  ;

需求： 将每个人的课程合并为一行数据

select t.name as '姓名',GROUP_CONCAT(t.course_name )  as '课程' from course t  group by t.name ;

修改分隔符及排序

select t.name as '姓名',GROUP_CONCAT(t.course_name  order by t.course_name SEPARATOR '#')  as '课程' from course t  group by t.name 

注意：使用 GROUP_CONCAT（）函数必须对源数据进行分组，否则所有数据会被合并成一行

SELECT  role_id, role_name, 

(
SELECT GROUP_CONCAT(menu_name) FROM sys_menu m, sys_role_menu n WHERE   m.menu_id = n.menu_id AND   n.role_id =a.role_id 

)

AS b  FROM sys_role a