entry_id int PK
member_id FK

SELECT member_id
FROM entries
GROUP BY member_id
ORDER BY RAND()
LIMIT 10

WHERE number > {randomNumber} ORDER BY number LIMIT 1`

name  entries   number  delta
bob        10     0.1    0.10
john        1     0.11   0.01
jim         5     0.16   0.05
fred       84     1      0.84