如何使用聚合T-SQL获取日期？

我正在尝试获取客户的总访问次数，以及上次访问日期和下次访问

SELECT 
  COUNT( VisitTracking.customerID) AS #VISIT, 
  Customers.title, 
  Customers.firstName, 
  Customers.LastName, 
  Company.companyName, 
  VisitTracking.DateVisited, 
  CONVERT(date,VisitTracking.nextVisit)AS nextVisit
FROM VisitTracking 
  INNER JOIN Customers ON VisitTracking.customerID = Customers.customerID 
  INNER JOIN Customer_Company ON Customers.customerID = Customer_Company.customerID 
  INNER JOIN Company ON Customer_Company.companyID = Company.companyID
GROUP BY 
  Customers.title, 
  Customers.firstName, 
  Customers.LastName, 
  Company.companyName,
  VisitTracking.DateVisited,
  VisitTracking.nextVisit

结果

#VISIT, title, firstName ,LastName, companyName, DateVisited, nextVisit
1,        Mr, Tom, Tom, Jedii design, 2012-11-09, 2012-11-14
2 ,       Mr, Sam, Tom, compudata, 2012-11-10, 2012-11-14
1,       Mr, Mike, Mike, compudata, 2012-11-10, 2012-11-14
1,       Mr, Mike, Mike, compudata, 2012-11-16 ,2012-11-23
1,       Mr, Ryan, Ryan, compudata, 2012-11-07 ,2012-11-09

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向我们展示一个表格结构，以及您想要的结果描述您希望上次访问和下次访问的结果，但结果是您有两次Mike先生，因此请精确说明您的期望。尝试从group by中删除DateVisited和nextVisit，并在select中设置MAX（VisitTracking.DateVisited）和MAX（CONVERT（date，VisitTracking.nextVisit））。您还没有问任何问题！请添加一个问题，如果可能，请添加一个包含一些示例数据的表结构，以及从数据中获得所需结果时遇到的问题。

SELECT 
  COUNT( VisitTracking.customerID) AS #VISIT, 
  Customers.title, 
  Customers.firstName, 
  Customers.LastName, 
  Company.companyName, 
  max(VisitTracking.DateVisited) as lastVisit, 
  max(CONVERT(date,VisitTracking.nextVisit)) AS nextVisit
FROM VisitTracking 
  INNER JOIN Customers ON VisitTracking.customerID = Customers.customerID 
  INNER JOIN Customer_Company ON Customers.customerID = Customer_Company.customerID 
  INNER JOIN Company ON Customer_Company.companyID = Company.companyID
GROUP BY 
  Customers.title, 
  Customers.firstName, 
  Customers.LastName, 
  Company.companyName