Mysql – How to get dates from a table while the date range is from the date belonging to another table

First, the condition WHERE date_field >= (CURDATE()-INTERVAL 1 MONTH) will not restrict your results to the current month. It will fetch all dates from 30-31 days ago up to the current date (and to the future, if there are rows with future dates in the table).

It should be:

WHERE date_field >= LAST_DAY(CURRENT_DATE) + INTERVAL 1 DAY - INTERVAL 1 MONTH
  AND date_field < LAST_DAY(CURRENT_DATE) + INTERVAL 1 DAY

Now, to the main question, to create 28-31 dates, even if the table has not rows for all the dates, you could use a Calendar table (with all dates, say for years 1900 to 2200) or create them on the fly, with something like this (the days table can be either a temporary table or you can even make it a derived table, with a somewhat more complicated query than this one):

CREATE TABLE days
( d INT NOT NULL PRIMARY KEY ) ;

INSERT INTO days
VALUES (0), (1), (2), ....
                  ..., (28), (29), (30) ;

SELECT 
    cal.my_date        AS date_field, 
    COALESCE(t.val, 0) AS val
FROM 
    ( SELECT 
          s.start_date + INTERVAL (days.d) DAY  AS my_date
      FROM 
          ( SELECT LAST_DAY(CURRENT_DATE) + INTERVAL 1 DAY - INTERVAL 1 MONTH
                       AS start_date,
                   LAST_DAY(CURRENT_DATE) 
                       AS end_date
          ) AS s
          JOIN days  
              ON  days.d <= DATEDIFF(s.end_date, s.start_date)
    ) AS cal
    LEFT JOIN my_table AS t 
        ON  t.date_field >= cal.my_date 
        AND t.date_field  < cal.my_date + INTERVAL 1 DAY ; 

The above should work for any type of the date_field column (date, datetime, timestamp). If the date_field column is of type DATE, the last join can be simplified to:

    LEFT JOIN my_table AS t 
        ON  t.date_field = cal.my_date ;

The easiest way is to have a calendar table, defined in the following way:

CREATE TABLE calendar
(
    a_day date PRIMARY KEY
) ;

... and filled with all the relevant dates (i.e.: all days from 1990-1-1 to 2100-12-31). For the sake of simplicity, we will fill it only with year 2013:

INSERT INTO 
     calendar (a_day)
VALUES
    ('2013-01-01'),
    ('2013-01-02'),
    ('2013-01-03'),
    ('2013-01-04'),
    ('2013-01-05'),
    -- everything up to
    ('2013-12-31') ;

At this point, you can just have a JOIN with the two tables; with the join condition not being an equality, but a range condition:

SELECT
     t.id, c.a_day
FROM
     t
     JOIN calendar c ON c.a_day BETWEEN t.start_date AND t.end_date 
ORDER BY
     t.id, c.a_day ;

... and get

id | a_day     
-: | :---------
 1 | 2013-01-14
 1 | 2013-01-15
 1 | 2013-01-16
 1 | 2013-01-17
 1 | 2013-01-18
 2 | 2013-02-01
 2 | 2013-02-02
 2 | 2013-02-03
 2 | 2013-02-04

You can see all the setup at dbfiddle here