select * from client_device where device_id = #{deviceId} select * from client_device where username = #{username} order by update_time desc insert into client_device(username, device_id, name, os, status, ip, location, last_active_at, create_time, update_time) values(#{username}, #{deviceId}, #{name}, #{os}, #{status}, #{ip}, #{location}, #{lastActiveAt}, now(), now()) update client_device set username = #{username}, name = #{name}, os = #{os}, status = #{status}, ip = #{ip}, location = #{location}, last_active_at = #{lastActiveAt}, update_time = now() where device_id = #{deviceId} delete from client_device where device_id = #{deviceId} select count(1) from client_device where username = #{username}