mysql实现动态查询表字段方式(返回JSON格式)

drop table if exists `field_config`;
create table `field_config`  (
  `text` varchar(255) character set utf8 collate utf8_general_ci null default null
) engine = innodb auto_increment = 5 character set = utf8 collate = utf8_general_ci row_format = dynamic;

insert into `field_config` values ('area_id');
insert into `field_config` values ('parent_id');
insert into `field_config` values ('area_name');
insert into `field_config` values ('area_type');

drop table if exists `ks_areas`;
create table `ks_areas`  (
  `area_id` smallint(6) unsigned not null auto_increment comment '地区id',
  `parent_id` smallint(6) unsigned not null default 0 comment '地区父id',
  `area_name` varchar(120) character set utf8 collate utf8_general_ci not null default '' comment '地区名称',
  `area_type` tinyint(1) not null default 2 comment '地区类型 0:country,1:province,2:city,3:district',
  primary key (`area_id`) using btree,
  index `parent_id`(`parent_id`) using btree,
  index `area_type`(`area_type`) using btree
) engine = innodb auto_increment = 3429 character set = utf8 collate = utf8_general_ci row_format = dynamic;

insert into `ks_areas` values (1, 0, '中国', 0);
insert into `ks_areas` values (2, 1, '北京', 1);
insert into `ks_areas` values (3, 1, '安徽', 1);
insert into `ks_areas` values (4, 1, '福建', 1);
insert into `ks_areas` values (5, 1, '甘肃', 1);
insert into `ks_areas` values (6, 1, '广东', 1);
insert into `ks_areas` values (7, 1, '广西', 1);

set @var = '1';
set @var1 = (select concat('json_object\(',group_concat(concat('\'',text,'\',',text)),'\)') from field_config);
set @strsql = concat('select ',@var1,' from ks_areas where area_id >', @var);
prepare stmt from @strsql;
execute stmt;

alter table ks_areas add test varchar(20) comment '测试字段';

insert into field_config value('test');