Adventure Works 2014 SQL 查询

Question

我正在使用 Adventure Works 2014 数据库编写 SQL 查询。

我想显示所有客户以及每个客户有多少订单。

我尝试单独编写每个 select 语句（见下文），但我希望能够将两个查询合并为一个。

select  s.CustomerID ,p.FirstName +' '+p.LastName as Name 
from Sales.Customer s,Person.Person p 
where s.CustomerID=p.BusinessEntityID
order by s.CustomerID


select CustomerID ,count(SalesOrderID) as OrdersCount
from Sales.SalesOrderHeader
group by CustomerID

Answer 1

 SELECT s.CustomerID ,
        p.FirstName +' '+p.LastName as Name,
        count(SalesOrderID)
 FROM Sales.Customer s
 JOIN Person.Person p 
   ON s.CustomerID=p.BusinessEntityID
 LEFT JOIN Sales.SalesOrderHeader so
   ON s.Customer_ID = so.Customer_ID  
 GROUP BY s.CustomerID ,
        p.FirstName +' '+p.LastName as Name 
 order by s.CustomerID

Answer 2

我添加 CONCAT 可能只是对你来说是新的东西。无论如何，OVER(PARTITION BY column_name) 子句被用作 GROUP BY 的替代品，因为您打印的列比 GROUP BY 子句所允许的要多。

Answer 3

Table Sales.Customer References:Person.人（PersonID -> BusinessEntityID）

SELECT s.CustomerID 
        ,p.FirstName +' '+p.LastName as Name
        ,COUNT(so.SalesOrderDetailID)
 FROM Sales.Customer s
 JOIN Person.Person p 
   ON s.PersonID=p.BusinessEntityID
 LEFT JOIN Sales.SalesOrderHeader h 
   ON h.CustomerID = s.CustomerID
 LEFT JOIN Sales.SalesOrderDetail so
   ON so.SalesOrderID = h.SalesOrderID
 GROUP BY s.CustomerID ,
        p.FirstName +' '+p.LastName
 order by s.CustomerID

Adventure Works 2014 SQL 查询

Adventure Works 2014 SQL Queries

mysql

sql

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