first_value和last_value具有空值

Question

我想获得前2本昂贵的书籍和2张昂贵的书价格使用first_value＆amp;last_value SQL Server

零的存在给出了不正确的最小价格价值，我希望最小价格忽略nulls

Select top 2 FIRST_VALUE(price) Over(Order by price) as MinPrice,
FIRST_VALUE(title) Over (order by price) as MinName,
LAST_VALUE(price) Over (order by price desc) as MaxPrice,
LAST_VALUE(title) over (Order by price desc) as MaxName
from titles; 

获取此输出

MINPrice    MINName                        Maxprice           MaxName
NULL       The Psychology of Computer        $22.95      But is it Friendly?
NULL       The Psychology of Computer        $21.59      Computer Phobic and 

我期望的结果应该是

Minprice     MinName                        Maxprice          Maxname           
$2.99        The Gourmet Microwave           $22.95       But is it Friendly?
$2.99        You can Combat stress          $21.59       Computer Phobic and 

所以我如何消除最低价格

Answer 1

您可以尝试

;WITH ctemin AS 
(
   SELECT TOP 2 price AS minprice, title AS mintitle FROM titles WHERE price IS NOT NULL ORDER BY price 
),
ctemax AS 
(
   SELECT TOP 2 price AS maxprice, title AS maxtitle FROM titles WHERE price IS NOT NULL ORDER BY price DESC
)
SELECT ctemin.minprice,ctemin.mintitle,ctemax.maxprice,ctemax.maxtitle FROM ctemax
INNER JOIN ctemin ON 1=1

Answer 2

SELECT min(value) FROM table WHERE value IS NOT NULL.

应该是这样的。