Which two statements are true regarding the COUNT function? (Choose two.)
A.
COUNT(*) returns the number of rows including duplicate rows and rows containing NULL value in any of
the columns
B.
COUNT(cust_id) returns the number of rows including rows with duplicate customer IDs and NULL value in
the CUST_ID column
C.
COUNT(DISTINCT inv_amt) returns the number of rows excluding rows containing duplicates and NULL
values in the INV_AMT column
D.
A SELECT statement using COUNT function with a DISTINCT keyword cannot have a WHERE clause
E.
The COUNT function can be used only for CHAR, VARCHAR2 and NUMBER data types
Explanation:
Using the COUNT Function
The COUNT function has three formats:
COUNT(*)
COUNT(expr)
COUNT(DISTINCT expr)
COUNT(*) returns the number of rows in a table that satisfy the criteria of the SELECT statement, including
duplicate rows and rows containing null values in any of the columns. If a WHERE clause is included in the
SELECT statement, COUNT(*) returns the number of rows that satisfy the condition in the WHERE clause.
In contrast,
COUNT(expr) returns the number of non-null values that are in the column identified by expr. COUNT
(DISTINCT expr) returns the number of unique, non-null values that are in the column identified by expr.