MYSQl 根据类型排序各取3个,随机取,sql怎么写?答:下面这个不知是否可行:create table books(`id` int, `name` varchar(16),`type` varchar(16));insert into books(`id`,`name`,type)select 1 as `id`, 'book11' as `name`, 'type1' as `type`union allselect 2, 'book12', 'type1'union allselect 3, 'book13', 'type1'...