Question

我正在尝试在SQL Server中编写一个查询，以查明customerID对每个客户是否有多行。请告诉我。

这是表结构

Customer table
-----------------------------------------
orderID          CustName      CustomerID
---------------------------------------
100               test           123456    
101               test           123456

Orders table
------------------------------------
pID               OrderID
-----------------------------------
1                 100        
2                 101

Answer 1

您可以使用GROUP BY查询来实现此目的：

select CustomerID, count(*) as NumDuplicates
from Customer
group by CustomerID
having count(*) > 1

Answer 2

查看您拥有的每位客户的数量：

SELECT COUNT(*), CustName, CustomerID
from Customer
Group by CustName, CustomerID

您可以使用having子句限制重复：

SELECT COUNT(*), CustName, CustomerID
from Customer
Group by CustName, CustomerID
having count(*) > 1

<强>更新

要获得订单成功的人：

select count(*), CustName, CustomerID
from(
  SELECT CustName, CustomerID
  from Customer, orders
  where customer.orderID = orders.orderID
  and orders.success = 1) subquery
group by subquery.CustName, subquery.CustomerID
having count(*) > 1;

Answer 3

select CustomerID, count(1)
  from Customer
 group by CustomerID
having count(1) > 1

具有重复记录的SQL查询

3 个答案: