Question

我们说Employee和Shippers表有以下数据。

EmployeeID  Name    
1           Davolio 
2           Fuller  
3           Leverling   
4           Peacock 
5           Buchanan
6           Suyama  
7           King    
8           Callahan
9           Dodsworth
10          West

ShipperID   ShipperName 
1           Speedy Express  
2           United Package  
3           Federal Shipping

以下查询按降序返回ShipperID。

select ShipperID from Shippers order by ShipperID desc;

现在，我想以与检索ShipperID相同的顺序（3,2,1）从Employee表中检索名称。我的预期输出为Leverling, Fuller, Davolio。

select Name from Employee where EmployeeID in (select ShipperID from Shippers order by ShipperID desc)

上述查询未按预期返回数据。如何解决这个问题？

更新：这不是按升序或降序排列记录。这只是我在这里发布的一个例子。为了更清楚，假设子查询将ShipperID作为2,3,1返回。现在我想从Employee表中检索记录，如Fuller, Leverling, Davolio

Answer 1

如果要保留订购，则必须加入这两个表。如果使用IN

，则不会保留子查询中的顺序

Answer 2

试试这个

select distinct Employee.Name from Employee 
inner join Shippers on Shippers.ShipperID=Employee.EmployeeID
order by Shippers.ShipperID desc

Answer 3

你试过吗

select Name from Employee where EmployeeID in (select ShipperID from Shippers ) order by ShipperID desc

Answer 4

select Name from Employee where EmployeeID in (select ShipperID from Shippers ) order by EmployeeID desc

作为employeeid = shipperid，您可以通过employeeid订购

Answer 5

如果您希望结果以特定顺序显示，那么您将不得不选择要按顺序排列的内容。在您的示例中，这意味着添加一列来定义发货人的订单，然后将其加入到员工表中，以便您可以相应地订购员工结果。

类似的东西：

WITH employees AS (SELECT 1 employeeid, 'Davolio' NAME FROM dual UNION ALL
                   SELECT 2 employeeid, 'Fuller' NAME FROM dual UNION ALL
                   SELECT 3 employeeid, 'Leverling' NAME FROM dual UNION ALL
                   SELECT 4 employeeid, 'Peacock' NAME FROM dual UNION ALL
                   SELECT 5 employeeid, 'Buchanan' NAME FROM dual),
      shippers AS (SELECT 1 shipperid, 'Speedy Express' shippername FROM dual UNION ALL
                   SELECT 2 shipperid, 'United Package' shippername FROM dual UNION ALL
                   SELECT 3 shipperid, 'Federal Shipping' shippername FROM dual)
-- end of mimicking your tables, see SQL below:
SELECT emp.employeeid,
       emp.name
FROM   employees emp
       INNER JOIN (SELECT shipperid,
                          CASE WHEN shipperid = 1 THEN 3
                               WHEN shipperid = 2 THEN 1
                               WHEN shipperid = 3 THEN 2
                          END order_id
                   FROM   shippers) shp ON emp.employeeid = shp.shipperid
ORDER BY shp.order_id ASC;

EMPLOYEEID NAME
---------- ---------
         2 Fuller
         3 Leverling
         1 Davolio

您的order_id列可能已经存在（例如时间戳列）或生成（通过上面演示的显式案例陈述，或使用row_number()分析函数）但是如果您想要结果要按特定顺序出现，您需要该列。

如何以与子查询相同的顺序检索数据？

5 个答案: