mysql pagination to display a page with a specific row in it

Now I have a question on mysql paging. A user's record is displayed on a table with many other user's record. an开发者_JAVA技巧d the table is sorted/paged. Now i need to display the page that containing the user's row directly after the user login. How can I achieve this? A simple thought would be firstly find out the rownum of the user, then do the paging accordingly, but I'm wondering if there are better ways to do it. thanks.

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Sample table for discussion

create table t_users (id int auto_increment primary key, username varchar(100));
insert t_users(username) values
('jim'),('bob'),('john'),('tim'),('tom'),
('mary'),('elise'),('karl'),('karla'),('bob'),
('jack'),('jacky'),('jon'),('tobias'),('peter');

The query to show the page on which the user is on, not specifically putting the user to the top of the page (which would have been a lot easier)

select username, id
from
  (select count(*) pos
   from t_users
   where username <= 'tobias') pos,
  (select @row:=@row+1 row, u.*
   from (select @row:=0) initvars, t_users u
   order by u.username, u.id) numbered
where floor((numbered.row + 3)/4) = floor((pos.pos+3)/4);

Notes:

1. The page size here is 4, the number 3 is the result of taking 1 off the page size
2. The username of the user who just logged in is 'tobias', which is used in the first sub-query
3. There had better be an index along the ORDER BY clause (in this case on username)
4. This will cause a table scan to fully row-number the last subquery

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select count(*) 
FROM table 
WHERE [sort_by_field] < [actual_records_value]