“ORDER BY … USING” clause in PostgreSQL

Question

The ORDER BY clause is decribed in the PostgreSQLdocumentation as:

ORDER BY expression [ ASC | DESC | USING operator ] [ NULLS { FIRST | LAST } ] [, ...]
         


        

Answer 1

Samples:

CREATE TABLE test
(
  id serial NOT NULL,
  "number" integer,
  CONSTRAINT test_pkey PRIMARY KEY (id)
)

insert into test("number") values (1),(2),(3),(0),(-1);

select * from test order by number USING > //gives 3=>2=>1=>0=>-1

select * from test order by number USING < //gives -1=>0=>1=>2=>3

So, it is equivalent to desc and asc. But you may use your own operator, that's the essential feature of USING