Use RAND() in User Defined Function

Question

I am trying to create a user defined function which calls the system RAND() function inside it, when I try to create the function it errors out with the followi

Answer 1

be carefull with RAND!

If you check this, you'll see, that multiple calls to this VIEW come all back with the same value. This is different with NEWID(). So if you really want random numbers it could be better to take NEWID() und do some "tricks" to get a number from - let's say - the first bytes...

CREATE VIEW vw_getRANDValue
AS
SELECT RAND() AS Value
GO
CREATE VIEW vw_getNEWID
AS
SELECT NEWID() AS Value
GO
CREATE FUNCTION dbo.Test() 
RETURNS TABLE AS
RETURN
WITH Numbers AS
(SELECT 1 AS x UNION SELECT 2 UNION SELECT 3) 
SELECT *
     ,(SELECT Value FROM vw_getRANDValue) AS myRandom
     ,(SELECT Value FROM vw_getNEWID) AS myNewid
FROM Numbers
GO
SELECT * FROM dbo.Test();
GO
DROP FUNCTION dbo.Test;
GO
DROP VIEW vw_getRANDValue;
GO
DROP VIEW  vw_getNEWID;
GO      

This is a result:

1. 0,684530884058892 D1809581-BBD1-4D23-A7F9-BC697E869BB0
2. 0,684530884058892 A4BAECDE-E993-46C1-B571-7440A713C371
3. 0,684530884058892 D7A1CB65-D2BC-41B2-990D-C3BC52B056A2

A view for a random BIGINT could look like this:

CREATE VIEW vw_getRandomBigInt
AS
SELECT CONVERT(BIGINT,CONVERT(VARBINARY(16),NEWID(),1)) * (-1) AS Value
GO

Hint: I checked this with many rows and it seems (just by sight), that this approach is not really random (all BIGINTs have the same width...). This seems to work properly:

CREATE VIEW vw_getRandomInt
AS
SELECT sys.fn_replvarbintoint(sys.fn_cdc_hexstrtobin(LEFT(REPLACE(CONVERT(VARCHAR(100),NEWID()),'-',''),4))) AS Value
GO