Is it possible to use Aggregate function in a Select statment without using Group By clause?

Question

So far I have written Aggregate function followed by Group By clause to find the values based on SUM, AVG and other Aggregate functions. I have a bit confusion in the Group

Answer 1

Yes you can use an aggregate without GROUP BY:

SELECT SUM(col) FROM tbl;

This will return one row only - the sum of the column "col" for all rows in tbl (excluding nulls).