Which two statements are true regarding the count function?
A.
The count function can be used only for CHAR, VARCHAR2, and NUMBER data types.
B.
Count (*) returns the number of rows including duplicate rows and rows containing null value in any of the
columns.
C.
Count (cust_id) returns the number of rows including rows with duplicate customer IDs and NULL value in
the CUST_ID column.
D.
Count (distinct inv_amt) returns the number of rows excluding rows containing duplicates and NULL values
in the INV_AMT column.
E.
A select statement using the COUNT function with a DISTINCT keyword cannot have a where clause.
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 theSELECT 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.
Not everyone realizes this, but the COUNT function will only include the records in the count where the value of expression in COUNT(expression) is NOT NULL. When expression contains a NULL value, it is not included in the COUNT calculations.
Confirmed B and D