If your table has an AutoNumber primary key field named ID, you could do it
with this query:
SELECT TOP 30 * FROM MyTable ORDER BY Rnd([ID]), ID;
Before you run the query, open the Immediate Window (Ctrl+G), and enter:
Randomize
How it works
==========
The Rnd() function generates a random number each time it's called. The
query optimiser doesn't bother calling the function on every row, unless you
pass in a field, so that's important even though Rnd() doesn't do anything
with the field.
This gives you random sorting in your query, and you wanted 30 results, so
we use TOP to select the first 30 from the random sort. Just in case Rnd()
should ever create 2 identical results, we add the primary key to the ORDER
BY clause, so Access can distinguish between them, and return exactly 30
records. (If there are multiple matches, it returns the ties as well.)
