看来您需要按月份和年份进行分组。否则，您将合并2010年1月和2011年1月：
SELECT YEAR(TransactionDate), MONTH(TransactionDate), SUM(Usage)
FROM YourTable
WHERE (TransactionDate Between [Some Start Date] AND[Some End Date])
GROUP BY YEAR(TransactionDate), MONTH(TransactionDate)
ORDER BY YEAR(Created), MONTH(Created)
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