oracle - SQL Query - Multiple Joins -

i'm having difficulty in joining same table(s) twice because of results returned incorrect.

the query below works fine. however, want change can return column of requirement type using value returned in requirement traced to column.

select    r.rq_req_id      "requirement traced from",           r.rq_req_name    "requirement name",           rty.tpr_name     "requirement type",           rtr.rt_to_req_id "requirement traced to"      req r left join req_trace rtr on        r.rq_req_id = rtr.rt_from_req_id, req_type rty     r.rq_type_id = rty.tpr_type_id ,       rty.tpr_name in ('tom', 'business process map', 'work instruction', 'functional', 'customer journey', 'business') order  1 

when add req , req_type tables in second time different aliases hundreds of rows returned instead of 28 expecting.

any appreciated.

never use commas in from clause. always use explicit join syntax.

you need add additional joins this:

select r.rq_req_id      "requirement traced from",        r.rq_req_name    "requirement name",        rty.tpr_name     "requirement type",        rtr.rt_to_req_id "requirement traced to",        rty2.tpr_name    "requirement type to", req r left join      req_trace rtr      on r.rq_req_id = rtr.rt_from_req_id left join      req_type rty      on r.rq_type_id = rty.tpr_type_id left join      req r r2      on r2.rq_req_id = rtr.rt_to_req_id left join      req_type rty2      on rty2.tpr_type_id = r2.rq_type_id rty.tpr_name in ('tom', 'business process map', 'work instruction', 'functional', 'customer journey', 'business') order 1;