sql server - Additional fields to results of INTERSECT -

i have query looks match 6 fields between 2 tables , return matches. query uses inner joins. i've been testing intersect replace this. thus,

select field1, field2, field3,...,field6 tablea intersect select field1, field2, field3,...,field6 tableb 

however, want add tablea.id , tableb.id results , can't quite written query won't take forever (relative original query). thoughts?

update: regretfully, added comment performance when first concern how write query. can see, believe main issue bad , incorrect query structure haven't been able improve. attempt:

select a.id, b.id     tablea inner join  (   select field1, field2, field3,...,field6   tablea   intersect   select field1, field2, field3,...,field6   tableb ) dupes on (   a.field1 = dupes.field1 ,   ...   a.field6 = dupes.field6 ) inner join tableb b (   b.field1 = dupes.field1 ,   ...   b.field6 = dupes.field6 ) 

a simple inner join on 6 fields return records both tables having common field values:

select a.id, b.id, a.field1, a.field2, a.field3, a.field4,         a.field5, a.field6 tablea inner join tableb b  on a.field1 = b.field1 , a.field2 = b.field2 , a.field3 = b.field3 ,     a.field4 = b.field4 , a.field5 = b.field5 , a.field6 = b.field6 

to optimize above query need set indices on columns used in on clause of inner join.