Oracle Database SQL — Question 8

Which two statements are true about the COUNT function? (Choose two.)

Answer options

• A. COUNT(*) returns the number of rows in a table including duplicate rows and rows containing NULLs in any column.
• B. It can only be used for NUMBER data types.
• C. COUNT(DISTINCT inv_amt) returns the number of rows excluding rows containing duplicates and NULLs in the INV_AMT column.
• D. COUNT(inv_amt) returns the number of rows in a table including rows with NULL in the INV_AMT column
• E. A SELECT statement using the COUNT function with a DISTINCT keyword cannot have a WHERE clause.

Correct answer: A, C

Explanation

Option A is correct as COUNT(*) indeed counts all rows, including duplicates and NULLs. Option C is also correct because COUNT(DISTINCT inv_amt) specifically excludes duplicates and NULLs in the counting process. Options B, D, and E are incorrect; COUNT can be used with various data types, COUNT(inv_amt) does not include NULLs, and COUNT with DISTINCT can have a WHERE clause.