mysql检查最后x个帖子的userID

Question

I have a php chat script on my site that I made, and I want to add in an anti-spam measure so that it wont post your message if the last 5 messages in the mysql table are by you.

Do I have to cycle through the last 5 with a recordset or is there a SQL statement that can just check this for me?

the table fields are just 'date' 'text' 'userid'

Answer 1

You can use a query like this to get how many of the last 5 messages where by the person in question.

select 
     sum(if(userid = '$user_id',1,0)) = 5 
     from (
         select userid from chat order by id desc limit 5
     );