正解:D,E,F
Single-row functions in SQL operate on each row independently and can modify the returned value:
Option A: Incorrect. Single row functions can be used in multiple parts of a SELECT statement, including SELECT, WHERE, and ORDER BY clauses.
Option B: Incorrect. Single row functions can accept more than one argument, such as the CONCAT function, which can accept multiple string arguments.
Option C: Incorrect. They return one result for each row processed, not per table.
Option D: Correct. Single row functions can take various types of arguments including column names, literals, variables, and other expressions.
Option E: Correct. Functions can be nested within other functions, allowing complex expressions and calculations.
Option F: Correct. The data type of the result can differ from the arguments' data types, such as the SUBSTR function returning a VARCHAR2 even when used on a number after converting it to a string.