Question

我是SQl的新手这是我的要求。

TableA 
operation route measurement
A         No    200
A         Yes   300
B         No    400
B         Yes   500

我希望将其作为结果

Operation MeasurementNo  MeasurementYes  MeasureDifference
A         200            300             100
B         400            500             100

因此必须对操作字段进行分组。同时，操作测量的两个值必须合并为一行。

The MeasureDifference = MeasurementYes - MeasurementNo。

使用SQL看起来并不难，但我只是一个新手。任何帮助表示赞赏。

Answer 1

或者使用分组和条件聚合：

SELECT
  operation,
  SUM(CASE route WHEN 'No'  THEN measurement END) AS MeasurementNo,
  SUM(CASE route WHEN 'Yes' THEN measurement END) AS MeasurementYes,
  SUM(CASE route WHEN 'Yes' THEN measurement END)
  - SUM(CASE route WHEN 'No'  THEN measurement END) AS MeasurementDifference
FROM atable t
GROUP BY
  operation

Answer 2

使用联接：

SELECT
    MNo.operation AS Operation,
    MNo.measurement AS MeasurementNo,
    MYes.measurement AS MeasurementYes,
    MYes.measurement - MNo.measurement AS MeasureDifference
FROM TableA AS MNo
JOIN TableA AS MYes
ON MNo.operation = MYes.operation
AND MNo.route = 'No'
WHERE MYes.route = 'Yes'

SQL从合并结果合并行并计算

2 个答案: