Sql 基于键的随机选择查询

是否可以根据关键点随机选择

我使用此查询随机查询：

SELECT * FROM tbl_news ORDER BY NEWID();

是否有这样的函数或方法来基于键进行随机查询：

使用相同的键：

使用另一个键：

---

你想要的是所谓的随机种子。看见种子使随机数可重复。我认为解决方法是使用seed并将它们放入一个表中，然后将这个表与您的表连接起来，以找到您想要的列表。请参见下面的示例

DECLARE @SEED INT = 100;
DECLARE @SIZE INT = 5;
-- url http://www.codeproject.com/Tips/811913/Generating-a-set-of-random-numbers-in-SQL-Server
WITH RandomNumbers (RowNumber, RandomNumber) AS (
    -- Anchor member definition
    SELECT  1                         AS RowNumber, 
            RAND(@SEED) AS RandomNumber
    UNION ALL
    -- Recursive member definition
    SELECT  rn.RowNumber + 1          AS RowNumber, 
            RAND( 1000000000* RAND(@SEED + rn.RowNumber))  AS RandomNumber
    FROM RandomNumbers rn
    WHERE rn.RowNumber < @SIZE
)
-- Statement that executes the CTE
SELECT  rn.RowNumber, rn.RandomNumber
FROM RandomNumbers rn
INNER JOIN tbl_news n
ON rn.RowNumber = n.ID
ORDER BY rn.RandomNumber

您可以使用，尽管它可能无法在大量行上出色地执行，尽管NEWID也不能，例如

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@DmitryBychenko：这不起作用，因为兰德公司将在下一个月返回相同的结果rows@DmitryBychenko不，一个键（例如15）定义了随机化的模式。只有NEWID，没有任何种子？@jarlh如果我们使用示例15，每次使用同一个键时，选择查询的顺序都是相同的。你的代码对我来说很好，但是有什么方法可以处理大量的行吗？我可能很快就跟你说过了，性能没有NEWID差多少，我刚刚在一个只有750k行的表上运行了一个比较，使用哈希字节的排序需要15秒才能完成，使用NEWID的排序平均需要14秒，每次运行5次

SELECT * FROM tbl_news ORDER BY NEWID(15);

5,1,3,2,4

SELECT * FROM tbl_news ORDER BY NEWID(36);

2,5,1,3,4

DECLARE @SEED INT = 100;
DECLARE @SIZE INT = 5;
-- url http://www.codeproject.com/Tips/811913/Generating-a-set-of-random-numbers-in-SQL-Server
WITH RandomNumbers (RowNumber, RandomNumber) AS (
    -- Anchor member definition
    SELECT  1                         AS RowNumber, 
            RAND(@SEED) AS RandomNumber
    UNION ALL
    -- Recursive member definition
    SELECT  rn.RowNumber + 1          AS RowNumber, 
            RAND( 1000000000* RAND(@SEED + rn.RowNumber))  AS RandomNumber
    FROM RandomNumbers rn
    WHERE rn.RowNumber < @SIZE
)
-- Statement that executes the CTE
SELECT  rn.RowNumber, rn.RandomNumber
FROM RandomNumbers rn
INNER JOIN tbl_news n
ON rn.RowNumber = n.ID
ORDER BY rn.RandomNumber

-- CREATE SAMPLE DATA
IF OBJECT_ID(N'tempdb..#tbl_news', 'U') IS NOT NULL DROP TABLE #tbl_news;
CREATE TABLE #tbl_news (NewsID INT IDENTITY);
INSERT #tbl_news DEFAULT VALUES;
INSERT #tbl_news DEFAULT VALUES;
INSERT #tbl_news DEFAULT VALUES;
INSERT #tbl_news DEFAULT VALUES;
INSERT #tbl_news DEFAULT VALUES;

-- DEFINE YOUR SORT KEY
DECLARE @Key INT = 15;

SELECT  *
FROM    #tbl_news
ORDER BY HASHBYTES('MD5', CONVERT(VARCHAR(10), NewsID + @Key));

-- SAME ORDER AS FIRST SELECT TO SHOW SORT IS REPEATABLE
SELECT  *
FROM    #tbl_news
ORDER BY HASHBYTES('MD5', CONVERT(VARCHAR(10), NewsID + @Key));


SET @Key = 36;

-- WITH A NEW KEY SHOW DIFFERENT ORDER
SELECT  *
FROM    #tbl_news
ORDER BY HASHBYTES('MD5', CONVERT(VARCHAR(10), NewsID + @Key));

-- BUT NEW ORDER IS STILL REPEATABLE
SELECT  *
FROM    #tbl_news
ORDER BY HASHBYTES('MD5', CONVERT(VARCHAR(10), NewsID + @Key));