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GATE Overflow Test Series | Databases | Test 1 | Question: 10

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

select count(*) + count(A) + count(B) from R
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1 Answer

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Count(*) will count including null but count(A) and count(B) will exclude NULL. So, we get $4+3+0 = 7.$
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