visit_id    visit_date  hosts   views
1   2016-08-16  12  45
2   2016-08-01  10  95
3   2016-08-04  24  56
4   2016-08-17  45  134

CREATE TEMPORARY TABLE last_days (
  day INT
);
INSERT INTO last_days
VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10),
       (11), (12), (13), (14), (15), (16), (17), (18), (19), (20),
       (21), (22), (23), (24), (25), (26), (27), (28), (29);

SELECT
  DATE(NOW() - INTERVAL l.day DAY) AS day
FROM
  last_days AS l;

CREATE TABLE visits (
  visit_id INT,
  visit_date DATE,
  hosts INT,
  views INT
);

INSERT INTO visits
VALUES
(1, '2016-08-16', 12, 45),
(2, '2016-08-01', 10, 95),
(3, '2016-08-04', 24, 56),
(4, '2016-08-17', 45, 134);

SELECT
  DATE(NOW() - INTERVAL l.day DAY) AS day,
  COALESCE(SUM(v.hosts), 0) AS hosts,
  COALESCE(SUM(v.views), 0) AS views
FROM
  last_days AS l
LEFT JOIN
  visits AS v
ON
  DATE(NOW() - INTERVAL l.day DAY) = v.visit_date
GROUP BY
  DATE(NOW() - INTERVAL l.day DAY);
+------------+-------+-------+
| day        | hosts | views |
+------------+-------+-------+
| 2016-07-19 |     0 |     0 |
...
| 2016-08-01 |    10 |    95 |
| 2016-08-02 |     0 |     0 |
| 2016-08-03 |     0 |     0 |
| 2016-08-04 |    24 |    56 |
| 2016-08-05 |     0 |     0 |
| 2016-08-06 |     0 |     0 |
| 2016-08-07 |     0 |     0 |
| 2016-08-08 |     0 |     0 |
| 2016-08-09 |     0 |     0 |
| 2016-08-10 |     0 |     0 |
| 2016-08-11 |     0 |     0 |
| 2016-08-12 |     0 |     0 |
| 2016-08-13 |     0 |     0 |
| 2016-08-14 |     0 |     0 |
| 2016-08-15 |     0 |     0 |
| 2016-08-16 |    12 |    45 |
| 2016-08-17 |    45 |   134 |
+------------+-------+-------+