How to use LIMIT to sample rows dynamically

I have a table as follows:

SampleReq	Group	ID
2	1	_001
2	1	_002
2	1	_003
1	2	_004
1	2	_005
1	2	_006

I want my query to IDs based on the column SampleReq, resulting in the following output:

Group	ID
1	_001
1	_003
2	_006

The query should pick any 2 IDs from group 1, any 1 IDs from group 2 and so on (depending on the column SampleReq).

I tried the query using LIMIT, but this gives me an error saying column names cannot be parsed to a limit.

SELECT Group, ID
FROM Table
LIMIT SampleReq
ORDER BY RAND()

Answer

One method is row_number():

select t.*
from (select t.*,
             row_number() over (partition by samplereq order by random()) as seqnum
      from t
     ) t
where seqnum <= 2 and id = 1 or
      seqnum <= 1 and id = 2;