Question

I have a report that displays a graph. The X axis uses the date from the below query. Where the query returns no date, I am getting gaps and would prefer to return a value. Is there any way to force a date where there are no records?

SELECT
    DATE(instime),
    CASE
        WHEN direction = 1 AND duration > 0 THEN 'Incoming'
        WHEN direction = 2 THEN 'Outgoing'
        WHEN direction = 1 AND duration = 0 THEN 'Missed'
    END AS type,
    COUNT(*)
FROM taxticketitem
GROUP BY
    DATE(instime),
    CASE
        WHEN direction = 1 AND duration > 0 THEN 'Incoming'
        WHEN direction = 2 THEN 'Outgoing'
        WHEN direction = 1 AND duration = 0 THEN 'Missed'
    END
ORDER BY DATE(instime)

Answer 1

One possible way is to create a table of dates and LEFT JOIN your table with them. The table could look something like this:

CREATE TABLE `datelist` (
 `date` DATE NOT NULL,
 PRIMARY KEY (`date`)
);

and filled with all dates between, say Jan-01-2000 through Dec-31-2050 (here is my Date Generator script).

Next, write your query like this:

SELECT datelist.date, COUNT(taxticketitem.id) AS c
FROM datelist
LEFT JOIN taxticketitem ON datelist.date = DATE(taxticketitem.instime)
WHERE datelist.date BETWEEN `2012-01-01` AND `2012-12-31`
GROUP BY datelist.date
ORDER BY datelist.date

LEFT JOIN and counting not null values from right table’s ensures that the count is correct (0 if no row exists for a given date).