Question

4. Why do we use Is Null criteria in a query?​

Answer 1

Answer:

A

database uses a special value for these holes: NULL. ... We do this by using the filter "is null" in the criteria row of our query. We use "is null" and not simply "null", like we would for any other filter, because for many database systems, NULL is a special value that isn't comparable to anything else.

Answer 2

Answer:

Suppose we wanted to know which experiments are missing hours data. We do this by using the filter "is null" in the criteria row of our query. We use "is null" and not simply "null", like we would for any other filter, because for many database systems, NULL is a special value that isn't comparable to anything else.

Explanation:

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