Question

Which of the following SQL function is used to count the non-NULL values in a column named column_name?

Options

• COUNT(*)

• COUNT(column_name)

• SUM(column_name)

• AVG(column_name)

Answer 1

COUNT(column_name)

Explanation:

In SQL, the COUNT(column_name) function counts only the non-NULL values in a given column.

• COUNT(*) → counts all rows (including those with NULL values).
• COUNT(column_name) → counts only rows where the column has a value (not NULL).