SQL: Select Closest Range Distance

Hello Guru,

I have below data

CREATE TABLE ZZ1

  (DOCNBR VARCHAR(10), PRIORITY NUMBER, LOC_NBR NUMBER

  );

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D1',5000,72);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D1',5000,172);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D1',5000,188);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D1',5000,475);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D2',5000,72);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D2',5000,165);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D2',5000,189);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D3',5000,474);

insert into ZZ1 (DOCNBR,PRIORITY,LOC_NBR ) values ('D4',5000,476);