使用SQL查询选择每月销售峰值

Question

我在psql中尝试使用Adventureworks数据库，我想尝试选择数据库中可用年份的峰值月度销售额。到目前为止，我的查询如下：

WITH ranked_monthly_sales AS (
SELECT
    RANK() OVER (PARTITION BY 
        to_char(soh.orderdate, 'MM') 
        ORDER BY SUM(sod.unitprice) DESC
        ) AS rank,
    to_char(soh.orderdate, 'MM') AS order_month,
    to_char(soh.orderdate, 'YYYY') AS order_year,
    SUM(sod.unitprice) AS unit_price
FROM
    sales.salesorderheader soh
INNER JOIN sales.salesorderdetail sod
    ON soh.salesorderid = sod.salesorderid
GROUP BY
    order_month,
    order_year
ORDER BY
    order_year,
    order_month
)
SELECT *
FROM ranked_monthly_sales
WHERE rank = 1
ORDER BY rank, order_year, order_month, order_year;

这将返回以下结果：

rank    order_month     order_year  unit_price
1       6               2013        2148488.3562
1       7               2013        2139025.3667
1       8               2013        1736638.0688
1       9               2013        2197327.4224
1       10              2013        2534203.6808
1       11              2013        2245166.9681
1       12              2013        2367052.5368
1       1               2014        2607573.234
1       2               2014        1336516.3606
1       3               2014        3489718.7278
1       4               2014        1796448.3395
1       5               2014        3172559.0484

但是，我正在尝试使用此计算字段获得类似于我在Tableau中创建的内容：

IF
    SUM([unit_price]) > LOOKUP(SUM([unit_price]),-1)
    AND
    SUM([unit_price]) > LOOKUP(SUM([unit_price]),1)
THEN
    'Peak'
END

使用此字段作为过滤器会给我带来截然不同的结果，如下表所示：

Month of order_date     Peaks   unit_price
December 2012           Peak    1,257,847.1714
August 2011             Peak    1,263,165.3553
September 2012          Peak    1,367,601.4629
March 2013              Peak    1,454,903.3623
March 2012              Peak    1,553,199.7152
June 2012               Peak    1,602,987.706
January 2012            Peak    1,955,076.8224
October 2011            Peak    1,983,602.0312
June 2013               Peak    2,148,488.3562
October 2013            Peak    2,534,203.6808
January 2014            Peak    2,607,573.234
May 2014                Peak    3,172,559.0484
March 2014              Peak    3,489,718.7278

有人可以帮我修复我的查询以获得我想要的东西吗？

非常感激。

Answer 1

如果您希望每月销售额大于上个月或下个月，请使用lead() / lag()：

WITH monthly_sales AS (
      SELECT to_char(soh.orderdate, 'YYYY-MM') AS yyyymm,
             SUM(sod.unitprice) AS sales
      FROM sales.salesorderheader soh INNER JOIN
           sales.salesorderdetail sod
           ON soh.salesorderid = sod.salesorderid
      GROUP BY to_char(soh.orderdate, 'YYYY-MM')
     )
SELECT *
FROM (SELECT ms.*,
             LAG(sales) OVER (ORDER BY yyyymm) as prev_sales,
             LEAD(sales) OVER (ORDER BY yyyymm) as next_sales,
      FROM monthly_sales ms
     ) ms
WHERE sales > prev_sales AND sales > next_sales