Which two tasks can your perform by using the TO_CHAR function? （）

A. SELECT TOTAL(*) FROM customer;
B. SELECT COUNT(*) FROM customer;
C. SELECT TOTAL(customer_id) FROM customer;
D. SELECT COUNT(customer_id) FROM customer;
E. SELECT COUNT(customers) FROM customer;
F. SELECT TOTAL(customer_name) FROM customer;

A. INSTR returns the numeric position of a named character.
B. NVL2 returns the first non-null expression in the expression list.
C. TRUNCATE rounds the column, expression, or value to n decimal places.
D. DECODE translates an expression after comparing it to each search value.
E. TRIM trims the heading of trailing characters (or both) from a character string.
F. NVL compares two expressions and returns null if they are equal, or the first expression of they are not equal.
G. NULLIF compares twp expressions and returns null if they are equal, or the first expression if they are not equal.

A. CREATE VIEW emp_vu AS SELECT * FROM employees WHERE department _ id IN (10,20);
B. CREATE VIEW emp_vu AS SELECT * FROM employees WHERE department_id IN (10,20) WITH READ ONLY;
C. CREATE VIEW emp_vu AS SELECT * FROM employees WHERE department_id IN (10,20) WITH CHECK OPTION;
D. CREATE FORCE VIEW emp_vu AS SELECT * FROM employees WITH department_id IN (10,20);
E. CREATE FORCE VIEW emp_vu AS SELECT * FROM employees WHERE department_id IN (10,20) NO UPDATE;