Well, you seem to be assuming that the results of all these queries can be processed together i.e. each record will have the same structure. If this is the case, then I'm puzzled why you need "10-20 different" queries to fetch them. Can you write a single query to do this e.g. using things like
SQL UNION to combine different subsets of data into one main query, or using a
SQL WITH clause (NB this is only available on some databases e.g., Oracle, PostgreSQL).
Alternatively, if you can't build a single query but you still want to do it all in one call to the database, you may need to look at using a stored procedure.
But I would start by analysing the data you are querying, the results you expect to get and what you want to do with the results, because it sounds strange that you need 10-20 different queries to fetch a single set of records that will all be processed together.