Question

如果我使用OR将条件条件串在一起，它将返回适合任何条件的结果，对吗？

例如，如果我键入

select * from TestTable
where Color='White' or Material='Cotton' or Gender='Female'
      or Length='Short'

它将给我从1个匹配到所有4个匹配条件的结果，对吧？

有什么办法知道每个返回结果匹配多少条件？

Answer 1

您需要在CASE中使用SELECT表达式。也许像这样：

CASE Color WHEN 'White' THEN 1 ELSE 0 END + 
CASE Material WHEN 'Cotton' THEN 1 ELSE 0 END + 
CASE Gender WHEN 'Female' THEN 1 ELSE 0 END + 
CASE Length WHEN 'Short' THEN 1 ELSE 0 END AS WhereMatched

Answer 2

一种方法是使用CASE表达式以及SUM窗口函数：

CREATE TABLE dbo.testtable(
      Color varchar(10)
    , Material varchar(10)
    , Gender varchar(10)
    , Length varchar(10)
);

INSERT INTO dbo.testtable VALUES
      ('White', 'Cotton', 'Female', 'Short')
    , ('White', 'Cotton', 'Female', 'Long')
    , ('White', 'Cotton', 'Male', 'Long')
    , ('White', 'Nylon', 'Male', 'Long')

SELECT *
    ,SUM(CASE WHEN Color='White' THEN 1 END) OVER(ORDER BY (SELECT 0)) AS ColorMatches 
    ,SUM(CASE WHEN Material='Cotton' THEN 1 END) OVER(ORDER BY (SELECT 0)) AS MaterialMatches 
    ,SUM(CASE WHEN Gender='Female' THEN 1 END) OVER(ORDER BY (SELECT 0)) AS GenderMatches
    ,SUM(CASE WHEN Length='Short' THEN 1 END) OVER(ORDER BY (SELECT 0)) AS LengthMatches
FROM TestTable
WHERE 
       Color='White'
    OR Material='Cotton' 
    OR Gender='Female'
    OR Length='Short';

符合多少条件？

2 个答案: