Multiple choice technology databases

COUNT(*) returns the number of items in a group - which of the below is correct?

  1. This includes NULL values and duplicate

  2. This includes NULL values but not the duplicates

  3. This does not include NULL values and duplicates

  4. None of the above

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A Correct answer
Explanation

The COUNT(*) function in SQL counts all rows that match the query criteria, including rows containing duplicate values and rows containing NULL values, unlike COUNT(column_name) which ignores NULLs.