Question

如果我有几个表，如下所示

Table1
-----------------------------
Name                      Qty
-----------------------------
John                       1
Paul                       2
               ...
Ringo                      1

和

Table2
-----------------------------
Forename    Surname      Cost
-----------------------------
John        Smith        123
John        Jones        815    
Paul        Smith        273
Paul        Jones        297
             ...
Ringo       Smith        755
Ringo       Jones        334

我希望构造一个查询，以便每个子集从Table2返回的数量由Table2.Cost排序并受Table1.Qty限制，返回类似于：

Results
-----------------------------
Forename    Surname      Cost
-----------------------------
John        Jones        815   
Paul        Jones        297
Paul        Smith        273
Ringo       Smith        755

有办法做到这一点吗？

Answer 1

试试这个

SELECT T.Forename,T.Surname, T.Cost
  FROM
     (
         SELECT *,
                ROW_NUMBER() OVER ( PARTITION BY Forename ORDER BY Cost DESC )  
                AS rn
           FROM Table2
      ) T
JOIN Table1 ON Table2.Foreman=Table1.Name
WHERE T.rn <=Qty;

Answer 2

SELECT Forename,
       Surname,
       Cost
  FROM
     (
         SELECT *,
                ROW_NUMBER() OVER ( PARTITION BY Forename ORDER BY Cost DESC )  
                AS rn
           FROM Table2
      )
WHERE rn = 1;

Answer 3

Updated and Tested: If it's about getting the highest cost from Table 2 depending upon Qty from Table 1, then use the following:

CREATE TABLE #table1 (name NVARCHAR(100), qty INT);
CREATE TABLE #table2 (forename NVARCHAR(100), surname NVARCHAR(100), cost INT);

INSERT INTO #table1 VALUES
('John', 1),
('Paul', 2),
('Ringo', 1);

INSERT INTO #table2 VALUES
('John', 'Smith', 123),
('John', 'Jones', 815 ),
('Paul', 'Smith', 273),
('Paul', 'Jones', 297),
('Ringo', 'Smith', 755),
('Ringo', 'Jones', 334);

WITH DATA AS (
SELECT t2.forename, t2.surname, t2.cost, t1.qty, 
rn = ROW_NUMBER() OVER (PARTITION BY t1.name ORDER BY t2.cost DESC)
FROM
  #table1 t1
  INNER JOIN #table2 t2 ON t1.name = t2.forename
)
SELECT d.forename, d.surname, d.cost
  FROM
DATA d
WHERE d.rn <= d.qty

Answer 4

create table #table1(name varchar(100), qty int)
create table #table2 (forename  varchar(100),  surname  varchar(100), cost int)

insert into #table1 values
('John',1),
('Paul',2),
('Ringo',1)

insert into #table2 values
('John'   ,     'Smith'      ,  123),
('John'    ,    'Jones'    ,    815 )   ,
('Paul'   ,     'Smith'    ,    273),
('Paul'   ,     'Jones'    ,    297),
('Ringo'  ,     'Smith'    ,    755),
('Ringo'  ,     'Jones'    ,    334)

select * from 
#table1 t1 cross apply 
    (select top (t1.qty) * from #table2 t2 where t1.name = t2.forename order by t2.cost desc) t

限制加入数量

4 个答案: