Try

;with cte as (select *, row_number() over (partition by GroupCondition order by NewID()) as RandomRow from People)

select * from cte where RandomRow <=25000

>Hi
>
>I have a task
>
>I want to select a list of people from my database.
>
>Total number to be selected 50000
>
>including all of two groups.
>
>Group 1 people who have joined 6 to 12 months ago.
>
>and
>
>Group 2 people who have previously paid
>
>so I imagine the group1 and group 2 will come to about 20000.
>
>How can I select a random selection of the rest.
>
>Any thoughts .
>
>Thanks
>
>Nick