mysql判断发布时间在多久前

发布时间是刚刚还是几分钟、几小时、几天前

语句：

if(timestampdiff(hour,refreshtime,now())<1,

if(timestampdiff(minute,refreshtime,now())=0,'刚刚',concat(timestampdiff(minute,refreshtime,now()),'分钟前')),

if(timestampdiff(hour,refreshtime,now())<24 ,concat(timestampdiff(hour,refreshtime,now()),'小时前'),

if(timestampdiff(day,refreshtime,now())<2,'昨天',concat(timestampdiff(day,refreshtime,now()),'天前')))) as refreshinfo