如何在SQL中获得一行三列（使用每个信使的成本总和）？

Question

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

Answer 1

您可以使用条件聚合来完成：

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

如何在SQL中获得一行三列（使用每个信使的成本总和）？

How to get one line and Three colums in SQL (using the sum of costs for each menssenger)?

sqlite

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aggregate-functions