Discussion
To define what columns should be displayed in an SQL SELECT statement:
Answer: A
Correct answer: use FROM to name the source table(s) and list the columns to be shown after SELECT.
Each clause has one job. FROM names the source - a table, several joined tables, a view or a subquery - and the SELECT list names the columns to be returned from it.
In relational terms these are the two basic operations: SELECT performs projection, choosing columns, and WHERE performs selection, choosing rows. USING exists in SQL but for a narrower purpose - naming the shared column in a join, as in JOIN orders USING (customer_id) - and never names the source table.
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