get all dates in the current month

i have a query in MySQL which serves me very well by getting all the records within the current month;

SELECT date_field,val FROM MY_TABLE WHERE date_field>=(CURDATE()-INTERVAL 1 MONTH);

The above query works well. so if this month we only had two records and 28 days it will bring only two records.

date_field | val
========================
2015-02-08 | 567
2015-02-09 | 345

But i want the number of records returned to be exactly the same as the number of days of the current month. if the current month has 28 days and only had two records it should bring;

date_field | val
========================
2015-02-01 | 0
2015-02-02 | 0
2015-02-03 | 0
2015-02-04 | 0
2015-02-05 | 0
2015-02-06 | 0
2015-02-07 | 0
2015-02-08 | 567
2015-02-09 | 345
2015-02-10 | 0
2015-02-11 | 0
2015-02-12 | 0
2015-02-13 | 0
2015-02-14 | 0
2015-02-15 | 0
2015-02-16 | 0
2015-02-17 | 0
2015-02-18 | 0
2015-02-19 | 0
2015-02-20 | 0
2015-02-21 | 0
2015-02-22 | 0
2015-02-23 | 0
2015-02-24 | 0
2015-02-25 | 0
2015-02-26 | 0
2015-02-27 | 0
2015-02-28 | 0

How can i modify my query to achieve the above result?

You can create a dynamic table of dates for the current month

SELECT date_field
FROM
(
    SELECT
        MAKEDATE(YEAR(NOW()),1) +
        INTERVAL (MONTH(NOW())-1) MONTH +
        INTERVAL daynum DAY date_field
    FROM
    (
        SELECT t*10+u daynum
        FROM
            (SELECT 0 t UNION SELECT 1 UNION SELECT 2 UNION SELECT 3) A,
            (SELECT 0 u UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
            UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
            UNION SELECT 8 UNION SELECT 9) B
        ORDER BY daynum
    ) AA
) AAA
WHERE MONTH(date_field) = MONTH(NOW());

NOTE: If you cut-and-paste the above query as is, it will generate the whole month for you

You then LEFT JOIN this to your original query

SELECT
    AAA.date_field,
    IFNULL(BBB.val,0) val
FROM
(
    SELECT date_field
    FROM
    (
        SELECT MAKEDATE(YEAR(NOW()),1) +
        INTERVAL (MONTH(NOW())-1) MONTH +
        INTERVAL daynum DAY date_field
        FROM
        (
            SELECT t*10+u daynum FROM
            (SELECT 0 t UNION SELECT 1 UNION SELECT 2 UNION SELECT 3) A,
            (SELECT 0 u UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
            UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
            UNION SELECT 8 UNION SELECT 9) B ORDER BY daynum
        ) AA
    ) AA WHERE MONTH(date_field) = MONTH(NOW())
) AAA LEFT JOIN (SELECT date_field,val FROM MY_TABLE) BBB
USING (date_field);

Give it a Try !!!

StackExchange Database Administrators Q#97773, answer score: 9