select cs_code, cs_pkkey from tbl_costs
    where (cs_date >= convert(datetime,'20111205') and cs_dateend <= convert(datetime,'20111205'))
     or (cs_date >= convert(datetime,'20111205') and cs_date <= convert(datetime,'20111205'))
     or (cs_dateend <= convert(datetime,'20111205') and cs_dateend >= convert(datetime,'20111205'))
     or (cs_date <= convert(datetime,'20111205') and cs_dateend >= convert(datetime,'20111205'))
     and cs_pkkey = 3619 and cs_prkey = 1051