Knowledge check

1.

Which function returns the number of distinct values of a particular column?

count()

dcount()

distinct()

2.

Which of the following can be used to summarize storm event data by week?

summarize ... by bin(StartTime, 7d)

summarize ... by StartTime

summarize ... by 1week

3.

Which function can be used with the summarize operator to return the median of storm events per state?

avg()

max()

percentiles()

4.

Which of the following best describes the let statement?

The let statement is useful for building complex expressions and using them as part of a query.

The let statement is useful for breaking up a complex expression into multiple parts. It defines a scalar or tabular variable, or a user-defined function that can be used multiple times within a query.

The let statement creates persisted functions as part of the database metadata (stored functions). They're invoked through a name, are provided with zero or more input arguments, and return a single value.

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