Question

我目前有一个表（预测），第一列包含两种类型的数据，即实际数据和预测数据。我想根据两个预测之间的月份来找到差异。该表如下所示：

Data     | Product |    Forecast M1 | Forecast M2 | Forecast M3
Actual        A              13          16             18
Actual        B              22          24             30
Forecast      A              15          14             21
Forecast      B              24          25             26

我想查询一个基于月比较两种产品的表，以显示实际值与预测值之间的差的绝对值，如下所示：

Product |    M1 difference | M2 difference | M3 difference
A              2                  2              3
B              2                  1              4

这是一个简单的查询还是需要创建一个新表？

Answer 1

这里有一个使用自我join和abs的选项：

select t1.product,
       abs(t1.forecastm1 - t2.forecastm1) as m1difference,
       abs(t1.forecastm2 - t2.forecastm2) as m2difference,
       abs(t1.forecastm3 - t2.forecastm3) as m3difference
from prediction t1
    join prediction t2 on t1.product = t2.product
where t1.data = 'Actual' 
    and t2.data = 'Forecast'

Answer 2

您可以使用如下查询：

SELECT act.Product
     , act.M1 - forc.M1 AS M1Diff
     , act.M2 - forc.M2 AS M2Diff
     , act.M3 - forc.M3 AS M3Diff
FROM #notnormal AS act
    INNER JOIN #notnormal AS forc ON forc.Product = act.Product
                                     AND act.Data = 'Actual'
                                     AND forc.Data = 'Forecast';

这是我设置用来显示它的模式：

CREATE TABLE #notnormal
(
    Data VARCHAR(10)
  , Product CHAR(1)
  , M1 SMALLINT
  , M2 SMALLINT
  , M3 SMALLINT
);
INSERT INTO #notnormal
(
    Data
  , Product
  , M1
  , M2
  , M3
)
VALUES
('Actual', 'A', 13, 16, 18)
, ('Actual', 'B', 22, 24, 30)
, ('Forecast', 'A', 15, 14, 21)
, ('Forecast', 'B', 24, 25, 26);

根据日期找出两种产品之间的差异

2 个答案: