GATE Overflow Test Series | Databases | Test 1 | Question: 7

Question

Given the following relation $R$
$$\textbf{R}$$$$\begin{array}{|c|c|c|c|c|c|c|}
\hline 
\textbf{A} & \textbf{B} \\
\hline
1 & \text{NULL}
\\ \hline
1 & \text{NULL}
\\ \hline
\text{NULL} & \text{1}
\\ \hline
4 & \text{NULL}
\\ \hline
\end{array}$$
The output of the following query will be ____________

select sum(A) + avg(A) + sum(B) + avg(B) from R

Answer 1

Except for $\text{count}(^{\ast}) ,$ aggregate functions ignore null values.

Now, $\text{sum(A) } = 6, \text{avg(A)} = \dfrac{6}{3} = 2,\text{sum(B) } = 1, \text{avg(B)} = \dfrac{1}{1} = 1.$

$\therefore \text{sum(A) } + \text{avg(A)} + \text{sum(B) } + \text{avg(B)} = 6 + 2 + 1 + 1 = 10.$

So, the correct answer is $10.$