SQL Randomise rows based on date and int to only change results order daily

Question

I would like to generate a "random" integer for each row returned from a select statement where the random int only changes once per day (before and after 4am).

Example

declare @Date datetime

set @Date = dateadd(dd, 8, GETDATE())

declare @DateNumber int

set @DateNumber = LEFT(CONVERT(VARCHAR(8), @Date, 112),10) 
+ cast(CASE WHEN DATEPART(hh, @Date) > 4 THEN 1 ELSE 0 END as varchar(1))

declare @Customers table (Id int, Customer varchar(150), OrderNo int)

insert into @Customers (Id, Customer) values (1, 'Cust A'),  (2, 'Cust B'), 

(3, 'Cust C'), (4, 'Cust D'), (5, 'Cust E'), (6, 'Cust F'), (7, 'Cust G'), (8, 'Cust H'), (9, 'Cust I')

-- my 1st attempt which doesnt work

update @Customers set OrderNo = rand(@DateNumber) / rand(Id) * 100

select * from 
@Customers order by OrderNo 

The order of the results should remain constant until I change the dd value in the set @Date statement at the top.

Any ideas? Is this possible? (outside of calculating this daily via a SQL job)

---

updated solution with HABO's recomendation

declare @Date datetime = dateadd(hh, 36, GETDATE())

declare @DateNumber int = LEFT(CONVERT(VARCHAR(8), @Date, 112),10) + 
cast(CASE WHEN DATEPART(hh, @Date) > 4 THEN 1 ELSE 0 END as varchar(1))

declare @Customers table (Id int, Customer varchar(150), OrderNo int)

insert into @Customers (Id, Customer) values (1, 'Cust A'),  (2, 'Cust B'), 
(3, 'Cust C'), (4, 'Cust D'), (5, 'Cust E'), (6, 'Cust F'), 
(7, 'Cust G'), (8, 'Cust H'), (9, 'Cust I')

declare @ThrowAway as Float = Rand(@DateNumber)

declare @ID int

set @ID = (select min(ID) from @Customers)

while @ID is not null

begin

    update @Customers set OrderNo = Floor(Rand() * 100) + 1 where ID = @ID


    set @ID = (select min(ID) from @Customers where ID > @ID) 

end 


select * from @Customers order by OrderNo 

Answer 1

When you provide a seed to RAND( Seed ) it will return the same result. If you use a seed value prior to your UPDATE query it will initialize the sequence. Thereafter just use RAND() without an argument. Something like:

declare @ThrowAway as Float = Rand( @DateNumber )
update @Customers
  set OrderNo = Floor( Rand() * 100 ) + 1

Do keep in mind that random values include duplicates.