The COUNT function in SQL is used to return the number of values within a specified column. It counts the total number of rows in a result-set or the number of non-NULL values in a specific column. Here's an explanation of each option:
Option A: values.
This is the correct answer. The COUNT function counts the total number of values (or rows) in a result-set or a specific column.
Option B: distinct values.
The COUNT function can also be used with the DISTINCT keyword to count the number of distinct (unique) values in a column. However, this is not the primary function of the COUNT function.
Option C: groups.
The COUNT function is not used to count groups. It is primarily used for counting values or rows.
Option D: columns.
The COUNT function does not count columns. It counts the number of values or rows.