如何使用UNION代替加入 [英] How to use UNION instead join

问题描述

我想更改下面的sql脚本并使用UNION



SELECT C.Customer_ID，C.Name，COUNT（I.Invoice_No）AS NumberOfInvoices，SUM（ I.Total）AS SumOfTotal

来自客户C

LEFT JOIN发票I ON C.Customer_ID = I.Customer_ID

GROUP BY C.Customer_ID ，C.Name



谢谢。



我尝试了什么：



我想创建一个临时表

解决方案

谢谢，这就是我做的事情

  SELECT  C.Customer_ID，C.Name， Null ， Null  
  FROM 客户C 
  UNION  
  SELECT  I.Customer_ID， Null ，COUNT（I .Invoice_No） AS  NumberOfInvoices，SUM（I.Total） AS  SumOfTotal 
  FROM 发​​票I 
  GROUP   BY  I.Customer_ID，C.Name 

阅读： SQL UNION Operator [ ^ ]



好​​教程网站：SQL教程 [ ^

I want to change the below sql script and use UNION

SELECT C.Customer_ID, C.Name, COUNT (I.Invoice_No) AS NumberOfInvoices, SUM (I.Total) AS SumOfTotal
FROM Customer C
LEFT JOIN Invoice I ON C.Customer_ID=I.Customer_ID
GROUP BY C.Customer_ID, C.Name

Thank you.

What I have tried:

I thought of creating a temp table

解决方案

Thanks, this is what I did

SELECT C.Customer_ID, C.Name, Null,Null
FROM Customer C
UNION
SELECT I.Customer_ID, Null, COUNT (I.Invoice_No) AS NumberOfInvoices, SUM (I.Total) AS SumOfTotal
FROM Invoice I
GROUP BY I.Customer_ID, C.Name

Read: SQL UNION Operator[^]

Good tutorial site: SQL Tutorial[^]

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