I have the following queries :
I am getting a different top result for each query.
As your query is not specifying an order, it is normal for results to be different each time - they are returning random rows from your table which meet the qualifying criteria.
To get the same top n returned you should add an ORDER BY
clause, for example:
SELECT *
FROM `datafusiontest-2897325.mergedquery.test_table`
ORDER BY date
LIMIT 10