思路 : 先求出 每个月 的销售量 然后累加起来
SELECT CONVERT(varchar(7), CreateDate, 120) AS num, CONVERT(varchar(4), CreateDate, 120) AS num2, PrePrice
FROM dbo.SER_Services
WHERE (CONVERT(varchar(4), CreateDate, 120) = CONVERT(varchar(4), '2018', 120))
将相同月份的数据求和
SELECT num AS Date, COUNT(num2) AS SerBills, SUM(PrePrice) AS SumPrice
FROM
(SELECT CONVERT(varchar(7), CreateDate, 120) AS num, CONVERT(varchar(4), CreateDate, 120) AS num2, PrePrice
FROM dbo.SER_Services
WHERE (CONVERT(varchar(4), CreateDate, 120) = CONVERT(varchar(4), '2018', 120))) AS a GROUP BY num
将数据 汇总