Update SQL table with random value from other table

Question

On Microsoft SQL Server 2008, I have a table with Products:

Id | Name | DefaultImageId

And one with Images:

Id | ProductId |

Answer 1

Try this one (on AdventureWorks):

It updates all rows of the person table with a new random name from the product table.

begin tran
--show initial state:
select top 25 * from person.person order by BusinessEntityID

update person.person
set 
FirstName = otherTable.Name
from 
(select BusinessEntityID, row_number() over (order by newid()) as row_num from person.person) p2
,(select ProductId, Name, row_number() over (order by newid()) as row_num from production.product) as otherTable
where 
person.person.BusinessEntityID=p2.BusinessEntityID 
and (p2.row_num%500)=(otherTable.row_num%500) -- deal with tables with different rowcount

--check results:
select top 25 * from person.person order by BusinessEntityID

rollback tran

Or try a similar query on SQL Fiddle: http://sqlfiddle.com/#!3/8b719/1