帮忙看一下几个简单的SQl查询语句~
Select   DISTINCT   Customers.CustomerID,Customers.CompanyName
From   Customers   JOIN   Orders   ON  
          (Customers.CustomerID=Orders.CustomerID)
Where   Orders.ShippedDate> 'May   1   1998 '
我不太明白的就是第二行和第三行!         帮忙解释一下   先谢过!    


------解决方案--------------------
Select DISTINCT Customers.CustomerID,Customers.CompanyName
From Customers JOIN Orders ON //内连接
(Customers.CustomerID=Orders.CustomerID)//将两个表ID相同进行连接
Where Orders.ShippedDate> 'May 1 1998 '