Which two statements are true about single row functions?

Single-row functions operate on single rows and return one result per row. Let's look at each option in the context of Oracle 12c SQL:

A. CONCAT: This function can only combine two values at a time. If you need to concatenate more than two values, you have to nest CONCAT functions or use the || operator.

B. MOD: The MOD function returns the remainder of a division operation, not the quotient.

C. CEIL: This function returns the smallest integer that is greater than or equal to a specified number. It works with both positive and negative numbers.

D. FLOOR: It returns the largest integer that is less than or equal to the specified number, not greater than or equal to.

E. TRUNC: This function can indeed be used with both NUMBER and DATE values to truncate them to a specified number of decimal places or to a particular component of a date.

References:

Oracle Database SQL Language Reference 12c Release 1 (12.1), Functions

Oracle Database SQL Language Reference 12c Release 1 (12.1), CONCAT Function

Oracle Database SQL Language Reference 12c Release 1 (12.1), MOD Function

Oracle Database SQL Language Reference 12c Release 1 (12.1), CEIL and FLOOR Functions

Oracle Database SQL Language Reference 12c Release 1 (12.1), TRUNC Function