What's the most efficient way to select the last n rows in a table without changing the table's structure?

Question

What\'s the most efficient way to select the last n number of rows in a table using mySQL? The table contains millions of rows, and at any given time I don\'t know how large

Answer 1

(Similar to "marco"s answer,)
my fav is the max()-function of MySQL too, in a simple one-liner, but there are other ways of sure:

SELECT whatever FROM mytable WHERE id > (SELECT max(id)-10 FROM mytable);

... and you get "last id minus 10", normally the last 10 entries of that table.

It's a short way, to avoid the a error 1111 ("Invalid use of group function") not only if there is a auto_increment-row (here id).
The max()-function can be used many ways.

Answer 2

SELECT * FROM table_name ORDER BY auto_incremented_id DESC LIMIT n

Answer 3

Maybe order it by the unique id descending:

SELECT * FROM table ORDER BY id DESC LIMIT n

The only problem with this is that you might want to select in a different order, and this problem has made me have to select the last rows by counting the number of rows and then selecting them using LIMIT, but obviously that's probably not a good solution in your case.

Answer 4

Here you can change table name and column name according your requirement . if you want to show last 10 row then put n=10,or n=20 ,or n=30 ...etc according your requirement.

select * from (select * from employee Order by emp_id desc limit n) a Order by emp_id asc;

Answer 5

Actually the right way to get last n rows in order is to use a subquery:

(SELECT id, title, description FROM my_table ORDER BY id DESC LIMIT 5) 
ORDER BY tbl.id ASC

As this way is the only I know that will return them in right order. The accepted answer is actually a solution for "Select first 5 rows from a set ordered by descending ID", but that is most probably what you need.

Answer 6

You would probably also want to add a descending index (or whatever they're called in mysql) as well to make the select fast if it's something you're going to do often.