MYSQL- Grab the last 5 rows AFTER sorting them by date

问题

I'm trying to execute a MYSQL command which grabs all the rows with the given UserID, sorts them by date, then returns only the first 5.

The command to sort is

ORDER BY date

and the command to get the last 5 is

WHERE ROWNUM <= 5

The WHERE comes before the ORDER, so it's backwards. So I figured I have to have a Mysql statement within a mysql statement.

Here is my attempt. I was getting an alias error, so i added the AS T1 to the command.

SELECT * FROM 
 (SELECT voting_id, caption_uid, voting_date, rating FROM voting 
   WHERE user_id = $inUserID  AS T1 
    ORDER BY voting_date) 
 WHERE ROWNUM <= 5 AS T2;

Any ideas?

回答1:

As you are working with MySQL, why not use the LIMIT clause, to only keep the first 5 results ?

select *
from your_table
order by your_column
limit 0, 5

Quoting a portion of the manual page for select :

The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants (except when using prepared statements).

With two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return.

回答2:

Try this:

select voting_id, caption_uid, voting_date, rating from voting
where user_id = $inUserID
order by voting_date
limit 5

Edit:

It is not clear whether you want the first or last 5. If you want the last five then the order by should be:

order by voting_date desc

回答3:

Try this query

Select columns from table_name where user_id =x  order by dateField desc Limit 5

回答4:

I am confuse with your title, and your question body. You mentioned last 5 records. in the first sentence of your question, it is first 5. A few words later, it is last 5 again.

If you want to get last 5, you may use this

select * from table order by date limit (select count(*)-5 from table),5

if you need to take care of less than 5 total records, you need to use the following:

select * from table order by date limit (select case when count(*)>=5 then count(*)-5 else 0 end case from table),5

If you can use stored procedure, the performance will be faster when you are in the 2nd example.

declare @total;
select @total = count(*) from `table`;
case when @total<5 then
@total=0;
else //mysql require case / else
end case;
select * from `table` order by `date` limit @total, 5

来源：https://stackoverflow.com/questions/9256024/mysql-grab-the-last-5-rows-after-sorting-them-by-date