Correct Answer: A,B
The CONCAT function and FLOOR function in Oracle SQL have specific behaviors:
A . CONCAT function joins two or more character strings into one string, making this statement true.
B . FLOOR function returns the largest integer that is less than or equal to the specified number, making this statement true.
C . While CONCAT can join two strings together, this statement is incomplete as it can join more than two.
D . INSTR can find the offset of a substring within a string, not just a single character.
E . INSTR starts searching the string from position 1 in Oracle SQL, not position 0.
F . FLOOR does return the largest integer less than or equal to the specified number, but it can be any integer, not just positive ones.
Reference:
Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Single-Row Functions"