Quick SQL question for sorting

I have this ordering sql at the end of my sql statement:

ORDER BY CASE WHEN LOWER(LEFT(E.name, 1)) BETWEEN 'a' AND 'z' 
              THEN 0 ELSE 1 END, E.name ASC

that orders the result this way: names starting with letters first and numbers later.

How can I add this: at first, names with a preference set on true, then all what I already have. ie: E.preference='true' will开发者_C百科 goes on the top.

Can't you just add the preference sort before your existing sort?

ORDER BY Case When e.Preference = 'true' then 0 else 1 end,
CASE WHEN LOWER(LEFT(E.name, 1)) BETWEEN \'a\' AND \'z\' THEN 0 ELSE 1 END, E.name ASC

Edit

Or if you want to have all preference = true first in any order then sort using your existing method then I think you could use:

Order By Case When e.Preference = 'true' Then 0  
         Else
              CASE 
                  WHEN LOWER(LEFT(E.name, 1)) BETWEEN \'a\' AND \'z\' THEN 1 
                  ELSE 2 END
         End, e.name asc

Edit 2

Taking this one step further you can have all preference = true first then sort these using your current method, then sort all the preference=false

Order By Case When e.Preference = 'true' Then 
                  CASE 
                  WHEN LOWER(LEFT(E.name, 1)) BETWEEN \'a\' AND \'z\' THEN 0 
                  ELSE 1 END  
         Else
              CASE 
                  WHEN LOWER(LEFT(E.name, 1)) BETWEEN \'a\' AND \'z\' THEN 2 
                  ELSE 3 END
         End, e.name asc

I'm not sure how this would affect the performance of the query though.

You can list multiple ORDER BY columns. So you could do ORDER BY e.preference, CASE WHEN LOWER(LEFT(E.name, 1)) BETWEEN \'a\' AND \'z\' THEN 0 ELSE 1 END, E.name ASC and if your non-preferred rows had NULL as preference then you'll get all preferred first (ordered by your existing criteria within that group) then all non-preferred (ordered by your existing criteria within that group)