我只想對前“n”個日期記錄的預測數量列求和。例如對于每個專案編號最早（或第一個）三個日期記錄
當前查詢：
SELECT gen.Item ,
gen.DemandDate ,
gen.ForecastQty
FROM reports.v_special_demand_800 gen
ORDER BY gen.Item, gen.DemandDate ASC
桌子
想要的結果
uj5u.com熱心網友回復：
為每條記錄分配一個行號，按專案磁區（這將為每個專案啟動一個新的行計數器）并按 DemandDate 排序。然后對行號 <= N 的記錄求和，按 Item 分組：
WITH CTE AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY Item ORDER BY DemandDate) as RowNum
FROM reports.v_special_demand_800
)
SELECT Item, SUM(ForecastQty)
FROM CTE
WHERE RowNum <= 3
GROUP BY Item
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標籤：sql sql-server 查询语句