如何在 SQL 中获取一行和三列（使用每个信使的成本总和）？

Posted 2023-02-16

【中文标题】如何在 SQL 中获取一行和三列（使用每个信使的成本总和）？

【英文标题】：How to get one line and Three colums in SQL (using the sum of costs for each menssenger)?

【发布时间】：2021-03-12 06:32:41

【问题描述】：

table screenshot

以下查询让我得到 3 行，但这不是我想要得到的，我想要得到 1 行和 3 列，你能帮我吗？

Select NoMess,
  case 
    when (NoMess = "1") Then (SELECT SUM (Port) from commande where NoMess = "1") 
    when (NoMess = "2") Then (SELECT SUM (Port) from commande where NoMess = "2") 
    when (NoMess = "3") Then (SELECT SUM (Port) from commande where NoMess = "3") 
  End as Port
From Commande 
Group by NoMess

【参考方案1】：

您可以使用条件聚合来做到这一点：

SELECT
  SUM(CASE WHEN NoMess = '1' THEN Port ELSE 0 END) AS column1,
  SUM(CASE WHEN NoMess = '2' THEN Port ELSE 0 END) AS column2,
  SUM(CASE WHEN NoMess = '3' THEN Port ELSE 0 END) AS column3
FROM Commande