CREATE TABLE t ( 
  id NUMBER(10) GENERATED ALWAYS AS IDENTITY NOT NULL PRIMARY KEY, 
  category NUMBER(10) NOT NULL, 
  counter NUMBER(10), 
  text VARCHAR2(10) NOT NULL 
)

INSERT INTO t (category, text) 
SELECT dbms_random.value(1, 10), dbms_random.string('a', 10) 
FROM dual 
CONNECT BY level <= 100

DECLARE 
  v_p1 NUMBER;
  v_p2 NUMBER;
BEGIN 
  UPDATE t 
  SET counter = nvl(counter, 0) + 1 
  RETURNING 
    percentile_disc(0.1) WITHIN GROUP (ORDER BY category),
    percentile_disc(0.1) WITHIN GROUP (ORDER BY category DESC)
  INTO 
    v_p1, 
    v_p2; 
     
  COMMIT; 
  dbms_output.put_line(v_p1); 
  dbms_output.put_line(v_p2); 
END;