PROC SQL allows a subquery (contained in parentheses) at any point in an expression where a simple column value or constant can be used. In this case, a subquery must return a single value, that is, ...

Learn what subqueries are, how to use them in SQL queries, and some best practices to follow. Subqueries can help you simplify complex queries, filter data, perform calculations, and join tables.

from product as p --using join select p.pid, p.pname, count (o.productid)as Total_Order from product as p inner join ProductOrder as o on p.pid=o.productId group by p.pname,p.pid -- sub Query to ...

This results in the following error: Error: You tried to reference "customerName" field from a subquery, which is a raw SQL field, but it doesn't have an alias declared. Please add an alias to the ...