Which two statements are true regarding single row functions? (Choose two.)
A. They accept only a single argument.
B. They can be nested only to two levels.
C. Arguments can only be column values or constants.
D. They always return a single result row for every row of a queried table.
E. They can return a data type value different from the one that is referenced.

關於單行函式，下面哪兩個選項是正確的？（選擇兩個）
A. 只接受一個引數。
B. 只能被巢狀兩級。
C. 引數只能是列值或者常量。
D. 對於查詢表的每一行總是返回一個結果行。
E. 返回值的資料型別可以與之前引用的資料型別不同。

A選項，不正確，單行函式可以接受一個或多個引數。
B選項，不正確，單行函式可以被巢狀多級。
C選項，不正確，引數還可以是變數和表示式。
D選項，正確，單行函式總是返回一個查詢表的每行一個結果行。
E選項，正確，單行函式可以返回一個不同的從一個參考資料型別值。

    Single-row functions return a single result row for every row of a queried table or view. These functions can appear in select lists, WHERE clauses, START WITH and CONNECT BY clauses, and HAVING clauses.

    Character functions that return number values can take as their argument any character data type. The character functions that return number values are:
ASCII
INSTR
LENGTH
REGEXP_COUNT
REGEXP_INSTR