Problem with sql query. Should i be using union?

Question

Have a problem that seems easy on paper but i'm having a big problem figuring out how best to write a single query.

I have a table

CREATE TABLE `profile_values` (  
  `fid` int(10) unsigned NOT NULL default '0',  
  `uid` int(10) unsigned NOT NULL default '0',  
  `value` text,  
  PRIMARY KEY  (`uid`,`fid`),  
  KEY `fid` (`fid`)  
) 

The point of this table is to store profile information on a user.
E.g. a typically row would look like this..

fid | uid | value  
__________________
1   | 77  | Mary  
11  | 77  | Poppins  
1   | 123 | Steve  
11  | 123 | Davis  

Note:

'fid' of '1' represents the first name  
'fid' of '11' represents the last name  
'uid' is a users id within the site.  

What I am trying to achieve is to bring back all uid's that satisfy the condition of first name like 'S%' and last name like 'D%'.
The reason i need this is because i have an autocomplete search box for users on the site.
So if i type 'S' in the search box i will see list of all users that begin with the letter 'S', if i now type a whitespace and 'D' i should now be able to see the list of users who match both conditions.

Does anyone have any idea how this can be accomplished? Thanks in advance.

Answer 1

select firstname.uid, fistname.value, lastname.value
from 
  profile_values firstname
  inner join profile_values lastname 
    on firstname.uid = lastname.uid
WHERE
  firstname.fid = 1
  AND lastname.fid = 11
  AND fistname.value like 'S%'
  AND lastname.value like 'D%'

or, with a users table

select users.uid, fistname.value, lastname.value
from 
  users
  inner join profile_values firstname
    on firstname.uid = users.uid
    AND firstname.fid = 1   
  inner join profile_values lastname 
    on lastname.uid = users.uid
    AND lastname.fid = 11
WHERE
  fistname.value like 'S%'
  AND lastname.value like 'D%'

EDIT:

Forgot to mention: union performs bad on many dbms. If you need a union, there is mostly something wrong with your database model. Use any other alternative before using union.