计算日期时间字段中的年和月条目

Question

I have a problem constructing a mysql query:

I have this table "tSubscribers" were I store the subscribers for my newsletter mailing list.

The table looks like this (simplified):

--
-- Table structure for tSubscriber
--
CREATE TABLE tSubscriber (
    fId INT UNSIGNED NOT NULL AUTO_INCREMENT,
    fSubscriberGroupId INT UNSIGNED NOT NULL,
    fEmail VARCHAR(255) NOT NULL DEFAULT '',
    fDateConfirmed DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
    fDateUnsubscribed TIMESTAMP NOT NULL DEFAULT '0000-00-00 00:00:00',
    PRIMARY KEY (fId),
    INDEX (fSubscriberGroupId),
) ENGINE=MyISAM;

Now what I want to accomplish is to have a diagram showing the subscriptions and unsubscriptions per month per subscriber group.

So I need to extract the year and months from the fDateConfirmed, fDateUnsubscribed dates, count them and show the count sorted by month and year for a subscriber group.

I think this sql query gets quite complex and I just can't get my head around it. Is this even possible with one query.

Answer 1

You will need two separate queries, one for subscriptions and other for unsubscriptions.

SELECT COUNT(*), YEAR(fDateConfirmed), MONTH(fDateConfirmed) FROM tSubscriber GROUP BY YEAR(fDateConfirmed), MONTH(fDateConfirmed)
SELECT COUNT(*), YEAR(fDateUnsubscribed), MONTH(fDateUnsubscribe ) FROM tSubscriber GROUP BY YEAR(fDateUnsubscribed), MONTH(fDateUnsubscribed)