Question

我的数据库中有三个表销售， SalesPeople 和设备：

销售

SaleDate   EmployeeID AppID Qty
---------- ---------- ----- -----------
2010-01-01 1412       150   1
2010-01-05 3231       110   1
2010-01-03 2920       110   2
2010-01-13 1412       100   1
2010-01-25 1235       150   2
2010-01-22 1235       100   2
2010-01-12 2920       150   3
2010-01-14 3231       100   1
2010-01-15 1235       300   1
2010-01-03 2920       200   2
2010-01-31 2920       310   1
2010-01-05 1412       420   1
2010-01-15 3231       400   2

销售人员

EmployeeID EmployeeName                   CommRate    BaseSalary  SupervisorID
---------- ------------------------------ ----------- ----------- ------------
1235       Linda Smith                    15          1200        1412
1412       Anne Green                     12          1800        NULL
2920       Charles Brown                  10          1150        1412
3231       Harry Purple                   18          1700        1412

电器设备

ID   AppType              StoreID Cost          Price
---- -------------------- ------- ------------- -------------
100  Refrigerator         22      150           250
110  Refrigerator         20      175           300
150  Television           27      225           340
200  Microwave Oven       22      120           180
300  Washer               27      200           325
310  Washer               22      280           400
400  Dryer                20      150           220
420  Dryer                22      240           360

如何制作排名的销售人员列表及其平均值销售佣金，不包括冰箱销售。

查询应显示：

EmployeeName                   Average Commission
------------------------------ ------------------
Harry Purple                   79.1999969482422
Linda Smith                    75.375
Charles Brown                  59.3333333333333
Anne Green                     42

Answer 1

SELECT sp.EmployeeName,
    COALESCE(AVG(s.Qty * (sp.CommRate / 100.0) * a.Price), 0) AS rank
FROM Sales s
LEFT JOIN SalesPeople sp
    ON s.EmployeeID = sp.EmployeeID
INNER JOIN Appliances a
    ON s.AppID = a.ID
WHERE a.AppType <> 'Refrigerator'
GROUP BY sp.EmployeeName
ORDER BY rank DESC

Answer 2

如果您想要包括所有员工 - 即使那些没有销售冰箱的员工 - 那么请使用LEFT JOIN并将冰箱过滤器放在ON条款中：

SELECT sp.EmployeeName,
       COALESCE(AVG(s.Qty * (sp.CommRate / 100.0) * a.Price), 0) as AvgCommRate
FROM SalesPeople sp LEFT JOIN
     Sales s
     ON s.EmployeeID = sp.EmployeeID LEFT JOIN
     Appliances a
     ON s.AppID = a.ID AND a.AppType <> 'Refrigerator'
GROUP BY sp.EmployeeName
ORDER BY AvgCommRate DESC;

三种方式加入SQL Server

2 个答案: