Null values while aggrigate function in query

Question

How aggrigate functions in query will behave in data contains NULL values.

I think answer should be D as all aggrigatre functions EXCEPT count will ignore NULL values. 

so, AVG will be 300 and count will be 4

Comments

I think all the aggregate functions ignore null values before there application.
So, 300,3 must be the answer?

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As per Korth "In general, aggregate functions treat nulls according to the following rule: All aggregate functions except count(*) ignore null values in their input collection".

And yes, given answer for this question is 300,3.

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ANS : 300 ,3

you can refer here.

http://www.sqlsnippets.com/en/topic-12656.html

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Refer https://gateoverflow.in/228692/count-takes-null-or-not

Answer 1

300 , 3 /. how avg works

avg = sum( marks) / count(marks) . = count ignore null values . so count marks gives 3

so 300

and count ( mobile number) = 3