[SQL] left join ?

[xyzii]

hi all,

I try

select purc.trn_no,purcsub.item_no,purcsub.qty,emp_no,emp_na
from purc left join purcsub on (purc.trn_no=purcsub.trn_no)
 left join emp on (purc.emp_no = emp.emp_no)

postgresql not run,please help,thank