The syntax of the MINUS clause is as follows:
select_statement MINUS select_statementselect_statement is a SELECT statement that does not contain an ORDER
BY or FOR UPDATE clause.
The MINUS operator computes the set of rows that are in the result of the left SELECT statement but not in the result of the right one.
The result of the MINUS clause does not contain duplicate rows.
Unless otherwise specified in parentheses, multiple MINUS operators in the same SELECT statement are evaluated from left to right. The MINUS clause binds at the same level as the UNION clause.