Which two statements are true about single row functions?
A) CONCAT : can be used to combine any number of values
B) MOD : returns the quotient of a division operation
C) CEIL : can be used for positive and negative numbers
D) FLOOR : returns the smallest integer greater than or equal to a specified number
E) TRUNC : can be used with NUMBER and DATE values
Answer：：CE
(解析：concat 函数只能连接两个字符串或者两个列的值。
ceil 函数向上取整数。
floor 函数向下取整。)
SQL> select ceil(-500.1) from dual;
CEIL(-500.1)
-500
SQL> select ceil(-500.99999) from dual;
CEIL(-500.99999)
-500
SQL> select floor(-500.1) from dual;
FLOOR(-500.1)
-501
原文：https://blog.51cto.com/13854012/2458921