Question

我的SQL查询还有其他问题。

我的任务是创建一个前十名员工的名单，其中1997年的销售额最高。到目前为止，我有这个简单的查询，向我显示员工名单以及他们已售出的订单。

SELECT  
    Orders.EmployeeID,
    Orders.OrderID
FROM
    Employees
JOIN 
    Orders ON Orders.EmployeeID = Employees.EmployeeID
ORDER BY 
    Orders.EmployeeID;

现在我想把这些数字分组，我需要知道每个员工在1997年做了多少销售。怎么做？

Answer 1

如果您按子查询的结果排序，则可以在不1和JOIN的情况下获得所需的结果：

GROUP BY

按销售交易数量计算前十名员工。

如果你需要来自SELECT TOP 10 * FROM Employees e ORDER BY ( SELECT COUNT(*) FROM Sales s WHERE s.EmployeeId=e.EmployeeId AND DATEPART(year, o.OrderDate)=1997 ) DESC的任何内容，比如计数，你需要走Sales路线：

GROUP BY

Answer 2

WITH CTE AS 
(
SELECT EmployeeId,COUNT(*) as cn,
       DENSE_RANK(ORDER BY COUNT(*) DESC) AS rn
FROM orders
WHERE DATEPART(year,OrderDate)=1997
GROUP BY EmployeeId
) 
SELECT e.*,COALESCE(o.cn,0) AS CountOrders
FROM Employees e
LEFT JOIN CTE o
ON e.EmployeeId=o.EmployeeId
WHERE o.rn<=10

Answer 3

它可以减少到这个

SELECT  top(10) EmployeeID, count(*) as cnt
FROM  Orders 
group by EmployeeID 
ORDER BY count(*) desc;

Northwind - 十大员工名单

3 个答案: