استفاده از متغیر در query

کد:

ResultSet resultSet = db.select("SELECT * FROM pgr_dijkstra('n" +
" SELECT gid AS id,n" +
" source::integer,n" +
" target::integer,n" +
" costvul::double precision AS costn" +
" FROM streetaxe',n" +
"49,41,false, false)a LEFT JOIN streetaxe b ON (a.id2 = b.gid) ");