>>>>The little problem is that I have my work on a separate computer, so it would be a bit of a hassle to post the code here.
>>>
>>>
>>>Take a look in RAND() function in BOL.
>>
>>I did, but could not figure out how to apply it to get a random record.
>
>

>SELECT TOP xxx  *, NEWID() as Test
>       FROM YoutTable
>ORDER BY NEWID()
>

>
>where xxx is any number from 1 to ...
>
>I thought you want to SET values not to SELECT records

This worked

update Schools set SchoolPhone = '718-805-9999' FROM schools INNER JOIN (SELECT TOP 20 School, NEWID() as Test
       FROM Schools ORDER BY NEWID()) RandSchools ON Schools.School = RandSchools.School

Nice technique.