What format is used for the DENSE_RANK function?

The DENSE_RANK function is used in SQL to assign ranks to rows within a partition of a result set, with the same rank being given to rows with equal values. The correct format of the DENSE_RANK function includes the OVER clause explicitly, which defines the order in which the ranking is applied to the result set.

Using the format DENSE_RANK() OVER (ORDER BY expr) specifies that the ranking should be computed according to the expression listed within the ORDER BY clause. This allows the function to precisely determine how to sequence the rows and assign ranks accordingly.

The presence of the OVER clause is crucial in this context because it indicates that the function is performing a windowed calculation, meaning it will consider the specified ordering of rows within the dataset to derive the ranks. This distinction is why the selection is correct, as it aligns with standard SQL syntax for window functions.

Other options do not correctly represent the syntax of the DENSE_RANK function with the required components. The absence of the OVER clause in those formats makes them invalid, as they do not follow the conventions outlined in SQL for this specific ranking function.