CREATE TABLE test AS
    SELECT 'value' || floor(dbms_random.VALUE(1, 4)) cola
          ,SYSDATE + LEVEL / (24 * 20) colb
    FROM dual
    CONNECT BY LEVEL < 1000;


SELECT hr
      ,COUNT(CASE
                 WHEN v.cola = 'value1' THEN
                  0
                 ELSE
                  NULL
             END) value1
      ,COUNT(CASE
                 WHEN v.cola = 'value2' THEN
                  0
                 ELSE
                  NULL
             END) value2
      ,COUNT(CASE
                 WHEN v.cola = 'value3' THEN
                  0
                 ELSE
                  NULL
             END) value3
FROM (SELECT t.*
            ,trunc(colb, 'hh') hr
      FROM test t
      WHERE colb BETWEEN SYSDATE AND SYSDATE + 1
      ORDER BY colb) v
GROUP BY hr;