Yes, multiple tables can be accessed in one SQL statement. That is one of the beautiful things of SQL. Your approach of using separate queries is way off base. Sure, it works, but what is the point.
Here is an example of accessing multiple tables in one statement (and there are MANY ways to do this):
(this is a simple join of two tables)
SELECT a.col1, b.col2
FROM tablea a, tableb b
WHERE a.col3 = b.col4
ORDER BY …
You need an introduction to SQL before you go any further. SQL, like so much in this world, is easy to misuse. Learn to put the work into the SQL. Make the SQL do the bulk of your processing.