friend表结构
DROP TABLE IF EXISTS FRIEND;
create table friend(
uid bigint not null comment '用户标识',
friend_uid bigint not null comment '申请加为好友的用户标识',
sys_create_date datetime not null comment '申请时间',
sys_last_update datetime not null comment '更新时间',
state tinyint not null comment '好友状态 0 ： 删除, 1:申请好友, 2 : 好友',
primary key(uid, friend_uid)
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT '好友表';
select friend_uid from
friend where state=2 and
uid in (select friend_uid from friend where uid=13 and state=2)
and friend_uid not in (select friend_uid from friend where uid=13 ) and friend_uid != 13 limit 6
uid为当前用户的ID，为id为13的用户查询二度人脉好友