Explanation:$concat behavior is well-defined regardless of the characters used. 9. ___________ returns either the non-null result of the first expression.
A. $Null
B. $ifNull
C. $ElseNull
D. None of the mentioned
Answer:A
Explanation:$concat behavior is well-defined regardless of the characters used. 9. ___________ returns either the non-null result of the first expression.
A. $Null B. $ifNull C. $ElseNull D. None of the mentioned
Explanation:$ifNull returns the result of the second expression if the first expression results in a null result. 10. Which of the following returns the value that results from applying an expression to the last document ?