In Oracle SQL, the following syntactical rules apply:
A). This query will result in an error because there is no comma separating the column names FIRST_NAME and LAST_NAME. The correct syntax should include a comma to separate the column names in the SELECT list.
B). This query is correctly formatted with a comma separating the column names, so it will not result in an error.
C). This query will result in an error because an alias defined in the SELECT list (ANNUAL_SALARY) cannot be used in the WHERE clause of the same query level. It must be repeated in the WHERE clause as 12
* SALARY.
D). This query will execute successfully because 12 * SALARY is directly used in the WHERE clause, and ANNUAL_SALARY is used in the ORDER BY clause, which is allowed.
E). This query is correct and will not result in an error. It uses 12 * SALARY in both the WHERE and ORDER BY clauses.
F). Similar to option C, this query will execute successfully because ANNUAL_SALARY is correctly used in the ORDER BY clause, and the WHERE clause does not attempt to reference the alias.
References:
* Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Database Object Names and Qualifiers"