Question

I have a search query that is dynamically compiled using NHibernate’s criteria query mechanism. The resulting SQL query might look like:

select 
    *
from
    sometable
where
(
    (
        firstname like 'chris%' or
        lastname like 'chris%'
    )
    and
    (
        firstname like 'vann%' or
        lastname like 'vann%'
    )    
)

The data in the table might look like:

FirstName         LastName
------------------------------
Chris             Smith
John              Vann
Chris             Vann

I’d like to order the results such that a row matching both sub-clauses in the where clause (i.e. firstname = Chris and lastname = Vann) is ranked higher than a row matching only one of the sub-clauses. Is this possible in standard SQL?

Edit: I greatly simplified the question to get down to the guts of the problem.

Answer 1

This is only a point to start. You can create a calculate priority column and sort rows by this column. The column is a indicator for well match row. Here a sample code writed for you:

create table #t (f varchar(10), l varchar(10) );

insert into #t values ('aa','ee'),('aa','ii'),('oo','ee');

select 
   *,
   case when f like 'aa%' then 1 else 0 end +
   case when l like 'aa%' then 1 else 0 end +
   case when f like 'ii%' then 1 else 0 end + 
   case when l like 'aa%' then 1 else 0 end 
   as priority
from #t
order by 
   priority desc

Results:

f  l  priority 
-- -- -------- 
aa ee 4        
aa ii 4        
oo ee 0 

For your schema may be something like:

select 
    *.
    case when firstname like 'chris%' and lastname like 'vann%' then 4 else 0 +
    case when firstname like 'chris%' and lastname not like 'vann%' then 3 else 0 +
    case when firstname not like 'chris%' and lastname like 'vann%' then 3 else 0 +
    ...
    as priority
from
    sometable
where
(
    (
        firstname like 'chris%' or
        lastname like 'chris%'
    )
    and
    (
        firstname like 'vann%' or
        lastname like 'vann%'
    )    
)
order by priority desc