参数月份选择：查询显示上个月、12个月前和最近12个月的平均值

Question

我想玩弄我的 Total_Sales 表。 这就是数据的样子（使用 SQL Server 2008 R2）

Name    Year  Month  Sales
------  ----  -----  -----
Alfred  2011  1      100
Alfred  2011  2      200
Alfred  2011  3      300
Alfred  2011  4      400
Alfred  2011  5      500
Alfred  2011  6      600
Alfred  2011  7      700
Alfred  2011  8      800
Alfred  2011  9      900
Alfred  2011  10     500
Alfred  2011  11     500
Alfred  2011  12     500

我要创建的 SQL 查询应该像这样显示数据：

Name    Year  Month  Sales Prev_Month Month_Last_Year_Sales Last_12_Month_AVG
------  ----  -----  ----- ---------- --------------------- -----------------
Alfred  2011  1      100   NULL       (year 2010, month 1)  (2010_01 to 2011_01)/(12)
Alfred  2011  2      200   100        (year 2010, month 2)  (2010_02 to 2011_02)/(12)
Alfred  2011  3      300   200        (year 2010, month 3)  (2010_03 to 2011_03)/(12)
Alfred  2011  4      400   300        (year 2010, month 4)  (2010_04 to 2011_04)/(12)
Alfred  2011  5      500   400        (year 2010, month 5)  (2010_05 to 2011_05)/(12)
Alfred  2011  6      600   500        (year 2010, month 6)  (2010_06 to 2011_06)/(12)
Alfred  2011  7      700   600        (year 2010, month 7)  (2010_07 to 2011_07)/(12)
Alfred  2011  8      800   700        (year 2010, month 8)  (2010_08 to 2011_08)/(12)
Alfred  2011  9      900   800        (year 2010, month 9)  (2010_09 to 2011_09)/(12)
Alfred  2011  10     500   900        (year 2010, month 10) (2010_10 to 2011_10)/(12)
Alfred  2011  11     500   500        (year 2010, month 11) (2010_11 to 2011_11)/(12)
Alfred  2011  12     500   500        (year 2010, month 12) (2010_12 to 2011_12)/(12)

要复制上个月我正在使用这个：Copy prior month value and insert into new row

SELECT
TS.name,
TS.year,
TS.month,
TS.sales,
COALESCE(TS2.sales, 0) AS prior_month_sales
FROM
TotalSales TS
LEFT OUTER JOIN TotalSales TS2 ON
TS2.name = TS.name AND
(
    (TS2.year = TS.year AND TS2.month = TS.month - 1) OR
    (TS.month = 1 AND TS2.month = 12 AND TS2.year = TS.year - 1)
)

Prev_Month 中的 NULL 表示 Total_Sales 的开始时间是 2011 年的第 1 个月，因此此示例没有先前的数据。

我打算使用一个参数，您可以在其中选择一个月。
感谢您的帮助！

Answer 1

SELECT
  [this_month].*,
  [last_month].Sales        AS [prev_month_sales],
  [last_year].Sales         AS [month_last_year_sales],
  [yearly].AverageSales     AS [last_12_month_average]
FROM
  Total_Sales     AS [this_month]
LEFT JOIN
  Total_Sales     AS [last_month]
    ON  [last_month].Name = [this_month].Name
    AND (
         ([last_month].Year = [this_month].Year     AND [last_month].Month = [this_month].Month - 1)
      OR ([last_month].Year = [this_month].Year - 1 AND [last_month].Month = 12 AND [this_month].Month = 1)
    )
LEFT JOIN
  TotalSales     AS [last_year]
    ON  [last_year].Name  = [this_month].Name
    AND [last_year].Year  = [this_month].Year - 1
    AND [last_year].Month = [this_month].Month
CROSS APPLY
(
  SELECT
    AVG(Sales) AS AverageSales
  FROM
    Total_Sales
  WHERE
    Name = [this_month].Name
    AND (
            (Year = [this_month].Year     AND Month <= [this_month].Month)
         OR (Year = [this_month].Year - 1 AND Month >  [this_month].Month)
    )
)
  AS [yearly]

平均值不是除以 12 的值，因为上一年并不总是有 12 个月的数据。但是 AVG() 函数会为您解决这个问题。

另外，我强烈建议不要使用 YEAR 和 MONTH 字段。相反，我建议使用 DATETIME 字段来表示“开始月份”并使用 SQL Server 的日期函数...

Last Month : MonthStart = DATEADD(MONTH, -1, ThisMonth)
A Year Ago : MonthStart = DATEADD(YEAR,  -1, ThisMonth)
Last Year  : MonthStart > DATEADD(YEAR,  -1, ThisMonth) AND MonthStart <= ThisMonth

Answer 2

另一个我不知道的答案是否更快......

WITH sales AS (
  SELECT
    ROW_NUMBER() OVER (PARTITION BY Name ORDER BY Year, Month) AS month_id,
    *
  FROM
    yearly_sales
)
SELECT
  Name       = [this_month].Name,
  Year       = MAX([this_month].Year),
  Month      = MAX([this_month].Month),
  Sales      = MAX([this_month].Sales),
  Last_Month = MAX(CASE WHEN [13_months].month_id = [this_month].month_id - 1  THEN [13_months].Sales END),
  Last_Year  = MAX(CASE WHEN [13_months].month_id = [this_month].month_id - 12 THEN [13_months].Sales END),
  Yearly_AVG = AVG(CASE WHEN [13_months].month_id > [this_month].month_id - 12 THEN [13_months].Sales END)
FROM
  Sales        AS [this_month]
INNER JOIN
  Sales        AS [13_months]
    ON  [13_months].Name      = [this_month].Name
    AND [13_months].month_id <= [this_month].month_id
    AND [13_months].month_id >= [this_month].month_id - 12
GROUP BY
  [this_month].Name

Answer 3

来自 AceAlfred -
One problem I have run into, maybe you know a quick fix? When a employee has not booked his sales for a previous month there is no data to display for this individual. Is there a way to add a row with the missing employee, where the "sales" is set to 0 and still pull the data for the other rows? Ex. Year 2012 -- Month 1 -- Name Alfred -- Sales 0 -- Prev 500

一种方法是“修复”您的数据，确保其中始终包含值。我建议在填充数据的任何系统中都这样做。或者作为一个夜间批次检查没有输入他们的数据并为您保留 0 的人（如果/当真实数据到达时更新）。但如果你不能......

CREATE TABLE agent (id INT, name NVARCHAR(128), start_date DATETIME, leave_date DATETIME);
-- populate with your agents

CREATE TABLE calendar (year DATETIME, month DATETIME, day DATETIME);
-- populate with all dates you want to report on

CREATE TABLE sales (agent_id INT, month_start DATETIME, total INT);
-- populate with your data


WITH new_raw_data AS
(
  SELECT
    agent.id                  AS [agent_id],
    calendar.month            AS [month_start],
    COALESCE(sales.total, 0)  AS [total]
  FROM
    agent
  INNER JOIN
    calendar
      ON  calendar.month_start >= COALESCE(DATEADD(month, -1, agent.start_date), '2000 Jan 01')
      AND calendar.month_start <= COALESCE(agent.leave_date, '2079 Dec 31')
  LEFT JOIN
    sales
      ON  sales.agent_id    = agent.id
      AND sales.month_start = calendar.month_start
  WHERE
    calendar.month_start = calendar.day   -- Only use records for the start of each month
)
,
<your other queries, using the nicely cleaned data, go here.>