我想按日期来分类。我首先尝试使用VARCHARS:
GROUP BY (YEAR(join_date) AS VARCHAR(4)) + '-' + CAST(MONTH(join_date) AS VARCHAR(2))
但是把它们转换成varchar意味着我的分类就像2014.1 - 2014.11 - 2014.12 - 2014.2,我怎么才能按年月顺序对它们进行适当的排序呢?
SELECT Year(join_date) + MONTH(join_date) AS Date, COUNT(*) AS Count
FROM X
WHERE mtype ='A