SQL Server 2016

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create table WIRES (
  ID int not null primary key clustered, 
  WTYPE char(3) not null, 
  WSIZE int not null
);

create table PARTS(
  id int not null,
  PNAME varchar(50)  null,
  WIRES_ID int not null
)
insert into Wires(id, wtype,wsize)
values(1,'ch',1),(2,'Ty',3);

insert into Parts(id,pname,wires_id)
  values(1,null,1),
      (2,'bolt',1),
     (3,'Nut',2)
5 rows affected

SELECT w.WTYPE, w.WSIZE, p.PNAME
FROM WIRES as w
LEFT JOIN PARTS as p
ON w.ID = p.WIRES_ID
WHERE
 (
 p.pname is null
 and not exists(select 1 
             from parts as s
             where p.wires_id =s.wires_id
              and s.pname is not null
              and p.id <> s.id)
  )
or p.pname is not null


WTYPE
WSIZE
PNAME


ch
1
bolt

Ty
3
Nut